A Temperature Of 104 F Is Approximately Equal To? Top Answer Update

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Do you want to change Fahrenheit to Celsius or Celsius to Fahrenheit? Use our simple Celsius to Fahrenheit temperature converter, our temperature conversion tables, or calculate C to F or F to C yourself using the conversion formulas.

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About Fahrenheit and Celsius

The Fahrenheit temperature scale is named for the German physicist Daniel Gabriel Fahrenheit and is the temperature measurement commonly used by the United States (and associated territories) and by several nations in the Caribbean. On the Fahrenheit scale, water freezes at 32°F and boils at 212°F (at sea level).

The Celsius temperature scale—originally called Celsius and later renamed after Swedish astronomer Anders Celsius—is used almost everywhere else in the world. On the Celsius scale, water freezes at 0°C and boils at 100°C (at sea level).

F° to C°: Fahrenheit to Celsius conversion formula

To convert degrees Fahrenheit temperatures to Celsius, subtract 32 and multiply by 0.5556 (or 5/9).

Example: (50°F – 32) x 0.5556 = 10°C

Fahrenheit to Celsius conversion table Fahrenheit Celsius -40 °F -40 °C -30 °F -34 °C -20 °F -29 °C -10 °F -23 °C 0 °F -18 °C 10 °F – 12°C 20°F -7°C 32°F 0°C 40°F 4°C 50°F 10°C 60°F 16°C 70°F 21°C 80°F 27°C 90°F 32 °C 100 °F 38 °C

C° to F°: Celsius to Fahrenheit conversion formula

To convert temperatures in degrees Celsius to Fahrenheit, multiply by 1.8 (or 9/5) and add 32.

Example: (30°C x 1.8) + 32 = 86°F

Celsius to Fahrenheit conversion table Celsius Fahrenheit -40°C -40°F -30°C -22°F -20°C -4°F -10°C 14°F 0°C 32°F 10°C 50°F 20°C 68°F 30°C 86°F 40°C 104°F 50°C 122°F 60°C 140°F 70°C 158°F 80°C 176°F 90°C 194°F 100° C212°F

Other conversions

What is the wet bulb temperature?

The wet bulb is the lowest temperature in the air that can only be reached by evaporation. Wet-bulb temperature is the lowest temperature that any portion of air can reach using only evaporative cooling. The wet-bulb temperature only becomes normal at 100% humidity. When the humidity in the air decreases, the wet bulb temperature will be lower than the normal temperature.

The formula for calculating wet bulb temperature is on the line.

Tw = T * arctan[0.151977 * (rh% + 8.313659)^(1/2)] + arctan(T + rh%) – arctan(rh% – 1.676331) + 0.00391838 *(rh %)^(3/2) * arctane (0.023101 * rh%) – 4.686035

Where,

Tw is the wet bulb temperature

T is the air temperature, which can be measured with a thermometer

rh% is the relative humidity. It is the ratio of the amount of water vapor in the air to the amount of water at the given temperature

Wet Bulb Temperature: This is a type of apparent temperature. Wet bulb temperature is used to estimate the effect of humidity, temperature, sunlight and wind speed on humans. The temperature equation for the wet globe is as follows:

WBGT = 0.7 * Tw + 0.2 * Tg + 0.1 * T

Where

Tg is the temperature of the globe thermometer

Another formula is WBGT = 0.7 * Tw + 0.3 * T

example

Question: If the ambient temperature is 25°C and the relative humidity is 40%, then find the wet bulb temperature?

Solution:

Given that

Temperature T = 25°C

Relative humidity RH = 40%

The formula for wet-bulb temperature is

Tw = T * arctan[0.151977 * (rh% + 8.313659)^(1/2)] + arctan(T + rh%) – arctan(rh% – 1.676331) + 0.00391838 *(rh %)^(3/2) * arctane (0.023101 * rh%) – 4.686035

Tw = 25 * arctan[0.151977 * (40 + 8.313659)^(1/2)] + arctan(25 + 40) – arctan(40 – 1.676331) + 0.00391838 *(40)^( 3/2) * arctan(0.023101). *40) – 4.686035

= 25 * arctan[0.151977 * 6.95080] + arctan(65) – arctan(38.323669) + 0.99128 * arctan(0.92404) – 4.686035

= 16.384°C

Therefore, the wet bulb calculator is 16.374 °C.

Physicscalc.Com has several calculators on different physics concepts in one place. Explore handy calculator tools to avoid tedious calculations and get results quickly.

temperature

Temperature Temperature – the measure of the average kinetic energy (KE) of a gas, liquid or solid. KE is kinetic energy.

. For air and other gases (only in the troposphere) it is common to consider the KE to be proportional to the number of molecular collisions. More collisions mean higher temperatures, while fewer collisions mean lower temperatures.

More collisions mean higher temperatures, while fewer collisions mean lower temperatures. Temperature is measured in degrees on the Fahrenheit, Celsius and Kelvin scales.

The Kelvin scale is called the absolute temperature scale because it is the only scale that measures energy directly. There are negative temperatures on the other two scales and it is impossible to have a negative energy.

Temperature profile of the atmosphere The atmosphere can be divided into four different temperature layers: Troposphere: contains most of the atmosphere, although it is very flat. Gravity causes the air to concentrate in this layer. The normal environmental loss rate (ELR) is negative (cooling with altitude) because the ground is the source of heat, but there may be temperature inversion resulting in a positive ELR (warming with altitude). Stratosphere: a layer of air above the tropopause that has a positive ELR due to ozone’s absorption of UV rays from the sun. Mesosphere: Above the stratopause, a layer of air with a negative ELR due to the absence of ozone and this layer being at extreme altitude. Thermosphere: Above the mesopause, this layer of air has so few air molecules that the KE is extremely high due to the very high velocities of these few air molecules. By definition, this implies a very high temperature, so the ELR is positive. In reality, the air doesn’t “feel hot” because there is so little air that you wouldn’t feel anything.

Methods of Heat Transfer Radiation – heat transferred by wave-like energy (e.g. photons) without molecular contact and without air movement. Ex. The earth is heated by the sun by radiation.

– Heat transmitted by wave-like energy (e.g. photons) without molecular contact and without air movement. Ex. The earth is heated by the sun by radiation. Conduction – heat transferred through molecule-to-molecule contact. Ex. Surface air warms by touching the warmer earth’s surface.

– Heat transferred via molecule-to-molecule contact. Ex. Surface air warms by touching the warmer earth’s surface. Convection – Heat transferred by moving air or water. Ex. Warm air rising into the atmosphere transfers heat from the lowest levels upwards.

Adiabatic process The process involving an ascending or descending parcel of air and the temperature changes associated with that movement.

When an air parcel rises, it moves to an area of ​​lower pressure at altitude. This lower pressure causes the air parcel to expand. The expansion gives the air molecules inside the pack more room to move. More space means fewer collisions between molecules. Less collisions mean less average CU. Lower average KE means cooler temperatures. Therefore, rising air always cools down.

. When an air parcel SINKS, it moves to an area below with higher pressure. This higher pressure causes the air packet to be compressed. The compression leaves less room for the air molecules inside the package to move. Less space means more collisions between molecules. More collisions means a larger average CU. Larger average KE means warmer temperatures. SINKING AIR ALWAYS WARMS .

. The rate of heating or cooling is constant and is called the adiabatic rate of decay (ALR). ALR = 5.5oF/1,000 ft. or 10oC/1 km.

Environmental Lapse Rate (ELR) The Environmental Lapse Rate is the rate of change of temperature with altitude between two altitudes in a layer of the atmosphere. The ELR is assumed to be constant between these two points. To calculate the ELR one needs two temperatures at two different altitudes (altitudes). To calculate, use the formula (T2-T1)/(H2-H1), where T is temperature and H is altitude. Answers must always be reduced to degrees F per 1,000 feet. Example:

The air at 2,000 feet is 40 degrees Fahrenheit, while the air at 6,000 feet is 10 degrees Fahrenheit. Calculate the ELR. Note the two points considered: T1 = 40F, H1 = 2,000 feet, T2 = 10F, H2 = 6,000 feet. Use the formula: (10F – 40F)/(6,000ft – 2,000ft) Result = -30F/4,000ft. Divide the top and bottom by 4 to reduce the ratio to F/1,000 feet. Answer: -7.5F / 1,000 feet.

Using the ELR to Estimate an “Intermediate” Temperature The previous ELR means that the air temperature cools by 7.5 F for every 1,000 feet of elevation. Therefore, one can use this ELR value to estimate any temperature between 2,000 and 6,000 feet. For example, if one wants to estimate the temperature at 4,000 feet, the ELR shows that there should be a 15 F (2 x 7.5) decrease moving from 2,000 feet to 4,000 feet. Since the air at 2,000 feet is 40 F, the air at 4,000 feet is 25 F (40 F – 15 F).

Dry bulb, wet bulb and dew point temperatures

The dry bulb, wet bulb, and dew point temperatures are important in determining the state of humid air. Knowing just two of these values ​​is sufficient to determine the condition – including the water vapor content and the sensible and latent energy (enthalpy).

Dry bulb temperature – T db

Dry bulb temperature, commonly referred to as air temperature, is the most commonly used property of air. When people refer to the temperature of the air, they are usually referring to its dry bulb temperature.

The dry bulb temperature essentially refers to the ambient air temperature. It is called “dry bulb” because the air temperature is indicated by a thermometer that is not affected by the humidity of the air.

The dry bulb temperature, T db , can be measured with an ordinary thermometer, exposed to air but shielded from radiation and moisture. Temperature is usually given in degrees Celsius (oC) or degrees Fahrenheit (oF). The SI unit is Kelvin (K). Zero Kelvin equals -273oC.

Dry bulb temperature is an indicator of heat content and is shown along the bottom axis of the psychrometric chart. Constant dry bulb temperatures appear as vertical lines on the psychrometric chart.

Wet bulb temperature – T wb

The wet bulb temperature is the temperature of adiabatic saturation. This is the temperature read by a moistened thermometer bulb exposed to the air flow.

Wet bulb temperature can be measured with a thermometer with the bulb wrapped in damp muslin. The adiabatic evaporation of water from the thermometer and the cooling effect is indicated by a “wet bulb” temperature that is lower than the “dry bulb” temperature in the air.

The rate of evaporation of the wet bandage on the bulb and the temperature difference between the dry and wet bulb depend on the humidity in the air. Evaporation is reduced when the air contains more water vapor.

The wet-bulb temperature is always lower than the dry-bulb temperature, but is the same as 100% relative humidity (the air is at the saturation line).

Combining the dry-bulb and wet-bulb temperatures on a psychrometric chart or Mollier chart gives the condition of humid air. Lines of constant wet-bulb temperatures run diagonally from top left to bottom right in the psychrometric diagram.

Dew point temperature – T dp

The dew point is the temperature at which water vapor begins to condense from air, the temperature at which air is fully saturated. Above this temperature, moisture remains in the air.

When the dew point temperature is close to the air temperature, the relative humidity is high, and when the dew point is far below the air temperature, the relative humidity is low.

When moisture condenses on a cold bottle from the refrigerator, the dew point temperature of the air will be higher than the temperature inside the refrigerator.

The dew point temperature can be measured by filling a metal can with water and ice cubes. Stir with a thermometer and observe the outside of the can. When the vapor in the air begins to condense on the outside of the can, the temperature on the thermometer is pretty close to the dew point of the actual air.

The dew point is indicated by the saturation line in the psychrometric chart.

An old psychrometer. These devices have been used to measure moisture content, or relative humidity, in the air for more than 100 years.

You may have noticed that humidity (the amount of water vapor in the air) makes a difference in how comfortable you are outside. When the humidity is high in summer, let’s say it’s “sultry”. When it’s cool and humidity is high, we can say it feels ‘clammy’. Humidity can make a warm day feel warmer and a cool day feel cold. You can observe the difference that humidity makes.

In this experiment you determine the relative humidity with wet and dry thermometers. Such a device is called a psychrometer.

What you need:

2 identical alcohol thermometers (Celsius)

Rectangle of heavy cardstock, about 10 inches long

strong band

fan

cotton balls

rubber band

Warm water

What to do:

1. Use tape to attach the thermometers to the cardboard rectangle about 5 inches apart. Make sure the bulb ends of the thermometers hang at least 1 inch below the edge of the box and the numbered sides of the thermometers are legible.

2. Place the thermometers in front of a small fan at moderate speed for 5 minutes and record the temperature readings. This verifies that your thermometers are calibrated and reading the same temperature under control conditions.

3. Soak several cotton balls in warm water and secure them around the bulb of a thermometer with the rubber band. Place the thermometers in front of the fan as before. After 5 minutes, record the “wet bulb” temperature reading and the “dry bulb” temperature reading.

4. To determine relative humidity, subtract the lower “wet bulb” temperature from the higher “dry bulb” temperature to determine the difference and compare to the chart.

Relative humidity (%) Dry bulb temperature (°C) Difference between wet bulb and dry bulb temperature (°C) 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 -20 100 28 -18 100 40 -16 100 48 -14 100 55 11 -12 100 61 23 -10 100 66 33 -8 100 71 41 13 -6 100 73 48 20 -4 100 77 54 32 11 -2 100 79 58 37 20 1 81 63 45 28 11 2 100 513 36 20 6 4 100 85 70 56 42 27 14 6 100 86 72 59 46 35 22 10 8 100 87 74 62 51 39 28 17 6 ​​10 100 2 8 8 12 100 88 78 67 57 48 2 198 1 100 89 79 69 60 41 33 25 16 8 1 100 90 71 62 54 45 37 14 7 1 18 100 91 72 64 56 48 26 26 26 26 26 26 26 26 26 26 26 26 26 26 26) 19 12 6 20 100 92 82 74 66 58 51 44 36 30 23 17 11 5 22 100 92 83 75 68 60 53 46 40 33 27 21 15 10 9 4 62 62 10 9 4 62 55 49 42 36 25 14 9 4 26 100 97 70 64 57 39 34 28 23 9 28 100 78 71 65 53 47 42 36 21 17 12 30 100 86 72 66 61 55 49 44 39 34 29 25 25 25 25 20 16

Results:

Although the air temperature has not changed, you should have noticed a lower temperature reading from the wet-bulb thermometer. This happens because as the cotton balls dried, some of the water evaporated (converted to water vapor).

This change of state from liquid water to water vapor requires some thermal energy from the surrounding atmosphere. The same thing happens when ice melts into liquid water. On the other hand, some heat is released when water vapor condenses back into liquid form or when water freezes into ice. This explains why you feel cold when you come out of a pool on a windy day, even though the air temperature is high, the water evaporating from your skin pulls the heat of evaporation out of your body and not out of the air!

Relative humidity is expressed as a percentage. It is the ratio of the current absolute humidity to the maximum possible absolute humidity at the current temperature. In other words, it’s the amount of moisture in the air compared to what the air can maximally “hold” at that temperature:

relative_humidity = 100% × current absolute humidity / maximum absolute humidity at current temperature

or to put it another way, the relative humidity is the ratio of the water vapor pressure Pw to the saturation water vapor pressure Pws at the given temperature:

relative_humidity = 100% × Pw / Pws

To understand this definition, you must also understand the meaning of absolute humidity. It’s just the water content of the air, expressed in grams per cubic meter:

absolute humidity = m/V, where m is the mass of water vapor and V is the volume of the mixture of air and water vapor.

With saturated air at 30 °C (86 °F), absolute humidity in the atmosphere ranges from ~0 to 30 grams per cubic meter.

Have you noticed that the formulas don’t take temperature into account?

dew point calculator

This calculator estimates the temperature to which air must be cooled in order to become saturated with water vapor and form dew.

Please provide two of the three variables below to calculate the third.

Air temperature Fahrenheit °F Celsius °C Kelvin Relative humidity Dew point temperature Fahrenheit °F Celsius °C Kelvin

What is moisture?

Humidity is defined as the amount of water vapor (water’s gaseous phase) in the air. It is an indicator of the presence of dew, frost, fog and precipitation. The maximum water vapor absorption of the air is influenced by the temperature; The higher the temperature, the more water vapor it can hold before reaching saturation.

Humidity is often discussed in terms of absolute humidity and relative humidity, as is the case on this calculator. The absolute humidity value is returned as part of the calculation results, but it is the relative humidity that is widely used in everyday life and used as part of the dew point temperature calculation.

Absolute humidity is the measurement of water content in air, typically in units of grams per cubic meter. It is calculated by dividing the total mass of water vapor by the volume of air. For the same amount of water vapor in the air, absolute humidity does not change with temperature for a fixed volume. When volume is not fixed, as in the atmosphere, absolute humidity changes in response to the changes in volume caused by changes in temperature and pressure.

Relative humidity compares the current ratio of absolute humidity to the maximum humidity at a given temperature and expresses this value as a percentage. The higher the percentage, the higher the humidity. It is affected by both temperature and pressure. With the same amount of water vapor, the relative humidity in cool air is higher than in warmer air.

Relative humidity is commonly used in weather reports and forecasts and is a good indicator of precipitation, dew, frost, fog and apparent temperature. Apparent temperature is the temperature perceived by humans. The higher the relative humidity in summer, the higher the perceived temperature. This is the result of higher humidity levels reducing the speed at which sweat evaporates, increasing the perceived temperature.

A relative humidity of 100% indicates that the air is saturated, which means that the water vapor in the air cannot continue to rise under current conditions under normal conditions. 100% relative humidity is also the point at which dew can form.

What is dew point?

The dew point is defined as the temperature at which a given volume of air at a given atmospheric pressure is saturated with water vapor, resulting in condensation and dew formation. Dew is the condensation that a person often sees on flowers and grass early in the morning. The dew point varies depending on the amount of water vapor in the air, with humid air resulting in a higher dew point than dry air. The higher the relative humidity, the closer the dew point is to the current air temperature, where 100% relative humidity means that the dew point corresponds to the current temperature. In cases where the dew point is below freezing (0°C or 32°F), the water vapor turns directly into frost and not dew.

While perception varies from person to person and people can get used to higher dew points to some extent, higher dew points are generally uncomfortable because the humidity prevents the proper evaporation of sweat and makes it harder for a person’s body to cool down. Conversely, lower dew points can also be uncomfortable, causing skin irritation and cracking, as well as drying out a person’s airways. The US Occupational Safety and Health Administration recommends that indoor air temperature should be maintained between 20 and 22°C with relative humidity of 20 to 60%.

Dew point is also considered in general aviation to calculate the likelihood of potential problems such as carburetor icing as well as fog. In some cases, devices known as dew point gauges are used to measure dew point over a wide temperature range. These devices consist of a polished metal mirror that is cooled when air is passed over it. The temperature at which dew forms on the mirror is the dew point.

How do I calculate the dew point when I know the temperature and relative humidity?

Relative humidity is the ratio of how much moisture the air contains to how much moisture it could hold at a given temperature.

This can be expressed in terms of vapor pressure and saturation vapor pressure:

RH = 100% x (E/It)

where, according to an approximation of the Clausius-Clapeyron equation:

E = E0 x exp[(L/Rv) x {(1/T0) – (1/Td)}] and

Es = E0 x exp[(L/Rv) x {(1/T0) – (1/T)}]

where E0 = 0.611 kPa, (L/Rv) = 5423 K (in Kelvin, over a flat water surface), T0 = 273 K (Kelvin)

and T is the temperature (in Kelvin) and Td is the dew point temperature (also in Kelvin).

So if you know the temperature, you can solve for Es and plug the equation for E into the relative humidity expression and solve for Td (dew point).

If you are interested in a simpler calculation that gives an approximation of the dew point temperature given the observed temperature and relative humidity, the following formula was suggested in a 2005 article by Mark G. Lawrence in the Bulletin of the American Meteorological Society :

Td = T – ((100 – RH)/5.)

where Td is the dew point temperature (in degrees Celsius), T is the observed temperature (in degrees Celsius), and RH is the relative humidity (in percent). Apparently this relationship is quite accurate for relative humidity values ​​above 50%.

See the article for more details:

Lawrence, Mark G., 2005: The Relationship Between Relative Humidity and the Dew Point Temperature in Moist Air: A Simple Conversion and Applications. Bull. america Meteor. Soc., 86, 225-233. doi: http://dx.doi.org/10.1175/BAMS-86-2-225

–Michael Bell

A triple point cell. Photo credit: NIST

Temperature is one of the most important and ubiquitous measurements in human life. For centuries we have continuously improved the systems, technologies, methods and units used to quantify and represent them. Now the next stage of this process has taken place. The Kelvin (K) – the SI unit of temperature – now has a radically new definition.

The Kelvin temperature scale – named after the famous British physicist Lord Kelvin (1824-1907) – rarely appears in everyday life. People are more familiar with the Fahrenheit and Celsius scales, which are used for most practical temperature measurements, e.g. in weather forecasting, food preparation, manufacturing, etc. Historically, both scales have focused on defined points such as the melting point of ice, the temperature of the human body, or the boiling point of water.

Kelvin is not expressed in degrees like Celsius or Fahrenheit. It is used alone to describe temperature. For example, “mercury loses all electrical resistance at a temperature of 4.2 Kelvin”.

A change of one Kelvin is the same temperature change as one degree Celsius, but the Kelvin scale is “absolute” in the sense that it starts at absolute zero, or what Kelvin and other scientists called “infinite cold.” (0K = -273.15 degrees C = -459.67 degrees F. Room temperature is about 70 degrees F, 21 degrees C, or 294 K.)

The concept of an absolute temperature scale is powerful; It differs from simple relative temperature, which talks about objects being hotter or colder than something else. The absolute, thermodynamic temperature of an object provides information about how much average kinetic energy (kinetic energy) its atoms and molecules have.

An important side note: according to 19th century classical physics, motion stops entirely at absolute zero. But according to quantum theory, introduced in the 20th century, matter at absolute zero has random motion called “zero-point motion,” thanks to a quantum concept known as the Heisenberg uncertainty principle, which dictates that an object’s position and momentum cannot at the same time be known with complete certainty. Zero-point motion is not considered heat-driven (thermal) motion and is therefore not part of the definition of thermodynamic or absolute temperature. At absolute zero there is only a quantum-mechanical zero-point movement.

The Kelvin scale is widely used in science, especially in the natural sciences. In everyday life, you usually encounter it as the “color temperature” of a lamp. An old-fashioned incandescent lamp that emits yellowish light has a color temperature of around 3,000K. In other words, its yellowish spectrum is very similar to what a hot object with a temperature of 3,000K would naturally emit. A lamp with a color temperature of 5,000K to 5,600K that contains more blue light is typically referred to as “daylight” or “full spectrum” because the temperature of the sun’s surface is about 5,800K. Many newly available LED lights fall within this range or even higher.

In 1954, the kelvin was defined as equal to the fraction 1⁄273.16 of the thermodynamic temperature of the triple point of water—the point at which water, ice, and water vapor coexist in equilibrium. This is a valuable common reference because for an accurate formulation of water at a given pressure, the triple point always occurs at exactly the same temperature: 273.16 K.

Extrapolating from the triple point temperature of water to very high or very low temperatures is problematic; 21 further limit points have been defined by international agreement, ranging from the freezing point of helium to the freezing point of copper.

However, the kelvin has been redefined in terms of Boltzmann’s constant, which relates the amount of thermodynamic energy in a substance to its temperature. When the revised SI was approved in November 2018, the new definition was:

The kelvin, symbol K, is the SI unit of thermodynamic temperature; its magnitude is set by fixing the numerical value of Boltzmann’s constant to be exactly 1.380649 × 10-23…J K-1 [joules per Kelvin].

If that sounds like a sip to you, you’re not wrong! To best understand the context and significance of this historical redefinition, it is helpful to learn more about the past, present, and future of temperature measurement.

Measurement levels in statistics

In order to perform statistical analysis of data, it is important to first understand the variables and what those variables are intended to measure. There are different levels of measurement in statistics, and the data measured with them can be roughly divided into qualitative and quantitative data.

First, let’s understand what a variable is. A quantity whose value changes across the population and can be measured is called a variable. For example, consider a sample of employed people. The variables for this population group can be industry, location, gender, age, qualifications, job type, and so on. The value of the variable is different for each employee.

For example, it is virtually impossible to calculate the average hourly rate for a worker in the United States. Therefore, a sample group is randomly selected to reasonably represent the larger population. The average hourly rate for this sample group is then calculated. Using statistical tests, you can infer the average hourly rate of a larger population.

The level of measurement of a variable determines the type of statistical test to use. The level of measurement is the mathematical nature of a variable, or in other words, how a variable is measured.

What are nominal, ordinal, interval and ratio scales?

Nominal, Ordinal, Interval and Ratio are defined as the four basic levels of measurement scales used to collect data in the form of surveys and questionnaires, each of which is a multiple choice question.

Each scale is an incremental measurement level, i. H. each scale performs the function of the previous scale, and all survey question scales like Likert, Semantic Differential, Dichotomous, etc. are the derivation of these 4 basic levels of variable measurement. Before we discuss all four levels of measurement scales in detail with examples, let’s take a quick look at what these scales represent.

The nominal scale is a naming scale where variables are simply “named” or labeled in no particular order. The ordinal scale has all of its variables in a specific order, aside from just naming them. The interval scale provides labels, order, and a specific interval between each of its variable options. The ratio scale has all the properties of an interval scale, with the addition that it can also accept the value “zero” for any of its variables.

Here are more of the four levels of measurement in research and statistics: nominal, ordinal, interval, ratio.

Nominal scale, also called categorical variable scale, is defined as a scale used to label variables into unique classifications and does not involve a quantitative value or quantitative order. This scale is the simplest of the four variable measurement scales. Calculations performed on these variables are useless as there is no numeric value of the options.

There are cases where this scale is used for the purpose of classification – the numbers associated with variables of this scale are just tags for categorization or subdivision. Calculations with these numbers are futile as they have no quantitative meaning.

For a question like:

where do you live

1- Suburbs

2- city

3- city

The nominal scale is commonly used in research surveys and questionnaires where only variable labels are meaningful.

For example, a customer survey with the question “Which smartphone brand do you prefer?”. Options: “Apple”-1, “Samsung”-2, “OnePlus”-3.

In this survey question, only the names of the brands are meaningful to the consumer researcher. No special order is required for these brands. However, while the nominal data is being collected, the researchers are performing analysis based on the associated labels.

In the example above, if a survey taker selects Apple as their preferred brand, the data entered and linked is “1”. This helped to quantify and answer the final question – how many respondents chose Apple, how many chose Samsung and how many chose OnePlus – and which is the highest.

This is the basis of quantitative research, and the nominal scale is the most basic research scale.

Nominal scale data and analysis

There are two main ways in which nominal scale data can be collected:

By asking an open-ended question, the answers to which can be coded to a corresponding number of labels set by the researcher. The other alternative to collecting nominal data is to include a multiple-choice question in which the answers are labeled.

In both cases, the analysis of the collected data is based on percentages or modes, i.e. H. the most frequently received answer to the question. It is possible for a single question to have more than one mode, as it is possible for there to be two common favorites in a target population.

Examples of nominal scales

gender

Political Preferences

Residence

What is your gender? What is your political preference? where do you live M- Male

W- Female 1- Independent

2- Democrat

3- Republican 1- Suburbs

2- city

3- city

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Nominal scale SPSS

In SPSS, you can specify the measurement level as scale (numerical data on an interval or ratio scale), ordinal, or nominal. Nominal and ordinal data can be either alphanumeric or numeric strings.

By default, when importing the data for any variable into the SPSS input file, it will be used as the scaling variable since the data is mostly numeric values. It’s important to change it to either nominal or ordinal, or keep it as a scale, depending on what variable the data represents.

Order scale: 2nd measuring level

The ordinal scale is defined as a variable measurement scale used to simply show the order of variables and not the difference between each variable. These scales are generally used to represent non-mathematical ideas such as frequency, satisfaction, happiness, some level of pain, etc. It’s pretty easy to remember how to implement this scale, since ordinal sounds similar to order. exactly the purpose of this scale.

The order scale retains descriptive qualities along with an intrinsic order, but has no origin of the scale and therefore distance between variables cannot be calculated. Descriptive qualities indicate marking properties similar to the nominal scale, in addition to which the ordinal scale also has a relative position of variables. The origin of this scale is absent, so there is no fixed start or “true zero”.

Ordinal Data and Analysis

Ordinal scale data can be presented in tabular or graphical formats to allow a researcher to conveniently analyze the data collected. Methods such as the Mann-Whitney U test and the Kruskal-Wallis H test can also be used to analyze ordinal data. These methods are generally implemented to compare two or more ordinal groups.

The Mann-Whitney U test allows researchers to determine which variable in a group is greater or less than another variable in a randomly selected group. During the Kruskal-Wallis H test, researchers can analyze whether or not two or more order groups have the same median.

Learn more about: Nominal vs. Ordinal Scale

Examples of ordinal scales

Workplace status, tournament team rankings, product quality order, and order of approval or satisfaction are some of the most common examples of the ordinal scale. These scales are commonly used in market research to collect and evaluate relative feedback on product satisfaction, changing perceptions on product upgrades, and so on.

For example, a semantic differential scale question like:

How satisfied are you with our services?

Very dissatisfied – 1

Dissatisfied – 2

neutral – 3

Satisfied – 4th

Very satisfied – 5

Here, the order of the variables is paramount, as is the labeling. Very dissatisfied is always worse than dissatisfied and satisfied is always worse than very satisfied. Here the ordinal scale is one step above the nominal scale – the order is relevant to the results and so is their naming. Analyzing results based on order along with name becomes a convenient process for the researcher. If they intend to get more information than they would gather with a nominal scale, they can use the ordinal scale.

This scale not only assigns values ​​to the variables, but also measures the rank or order of the variables, such as:

Grades

satisfaction

happiness

How satisfied are you with our services?

1- Very dissatisfied

2- Dissatisfied

3- Neural

4- Satisfied

5- Very satisfied

Interval scale: 3rd measurement level

The interval scale is defined as a numeric scale where the order of the variables and the difference between those variables are known. Variables with known, constant, and computable differences are classified using the interval scale. It is also easy to remember the primary role of this scale, “interval” indicates “distance between two units”, and that is exactly what the interval scale helps to achieve.

These scales are effective as they open doors for statistical analysis of the data provided. Mean, median, or mode can be used to calculate central tendency in this scale. The only downside to this scale is that there is no predetermined starting point or true zero value.

The interval scale has all the properties of the ordinal scale, plus it provides a calculation of the difference between variables. The main feature of this scale is the equidistant difference between objects.

For example, consider a Celsius/Fahrenheit temperature scale –

80 degrees is always higher than 50 degrees and the difference between these two temperatures is the same as the difference between 70 degrees and 40 degrees.

Also, the value 0 is arbitrary because there are negative temperature values ​​- making the Celsius/Fahrenheit temperature scale a classic example of an interval scale.

The interval scale is often chosen in research cases where the difference between variables is a mandate—which cannot be achieved with a nominal or ordinal scale. The interval scale quantifies the difference between two variables, while the other two scales are only able to assign qualitative values ​​to variables.

In contrast to the two previous scales, the mean and median values ​​can be evaluated in an ordinal scale.

In statistics, interval scales are often used because variables can not only be assigned numerical values, but calculations can also be carried out based on these values.

While interval scales are amazing, they don’t calculate the “true zero value,” which is why the next scale comes into the picture.

Interval data and analysis

All techniques applicable to nominal and ordinal data analysis are also applicable to interval data. Apart from these techniques, there are some analysis methods such as descriptive statistics, correlation regression analysis, which are used extensively to analyze interval data.

Descriptive statistics is the term for analyzing numerical data that helps to describe, represent, or summarize data in a meaningful way, and helps calculate the mean, median, and mode.

Examples of interval scales

There are situations when setting scales are considered interval scales.

Aside from the temperature scale, time is also a very common example of an interval scale because the values ​​are already fixed, constant, and measurable.

Calendar years and time also fall under this category of measurement scales.

Likert scale, Net Promoter Score, Semantic Differential Scale Bipolar Matrix Table, etc. are the most commonly used examples of interval scales.

The following questions fall under the interval scale category:

What is your family income?

What is the temperature in your city?

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Ratio scale: 4th measurement level

The ratio scale is defined as a variable measurement scale that not only produces the order of the variables, but also makes known the difference between variables along with information about the value of the true zero. It is calculated by assuming the variables have an option for zero, the difference between the two variables is equal, and there is a specific ordering between the options.

With the True Zero option, various inferential and descriptive analysis techniques can be applied to the variables. In addition to the fact that the ratio scale can do everything that a nominal, ordinal, and interval scale can do, it can also determine the value of absolute zero. The best examples of ratio scales are weight and height. In market research, a ratio scale is used to calculate market share, annual sales, price of an upcoming product, number of consumers, etc.

The ratio scale provides the most detailed information because researchers and statisticians can calculate central tendency using statistical techniques such as mean, median, mode, and methods such as geometric mean, coefficient of variation, or harmonic mean, which can also be used on this scale.

The ratio scale accommodates the properties of three other variable measurement scales, namely the labeling of the variables, the significance of the order of the variables, and a calculable difference between variables (which are usually equidistant).

Because of the existence of the true zero value, the ratio scale has no negative values.

To decide when to use a ratio scale, the researcher must observe whether the variables exhibit all of the characteristics of an interval scale along with the presence of the absolute zero value.

Mean, mode and median can be calculated using the ratio scale.

Ratio Data and Analysis

Basically, ratio scale data is quantitative in nature, which is why any quantitative analysis techniques such as SWOT, TURF, crosstab, conjoint, etc. can be used to calculate ratio data. While some techniques like SWOT and TURF analyze ratio data in a way that allows researchers to create roadmaps of how products or services can be improved, and cross-tabs will be helpful in understanding whether new features will be helpful for the target market or not.

Examples of ratio scales

The following questions fall under the Ratio Scale category:

How tall is your daughter now? Less than 5 feet. 5 ft 1 in – 5 ft 5 in 5 ft 6 in – 6 ft More than 6 ft

What is your weight in kilograms? Less than 50 kg 51-70 kg 71-90 kg 91-110 kg More than 110 kg

Learn more about: Interval vs. Ratio Scale

Summary – measurement planes

The four data measurement scales – nominal, ordinal, interval and ratio – are often discussed in academic teaching. The easy-to-remember chart below might help you in your stats test.

Offers: Nominal Ordinal Interval Ratio The order of variables is established – Yes Yes Yes Mode Yes Yes Yes Yes Median – Yes Yes Yes Mean – – Yes Yes Difference between variables can be evaluated – – Yes Yes Addition and subtraction of variables – – Yes Yes Multiplication and Division of variables – – – Yes Absolute zero point – – – Yes

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Typical human temperature range

The normal human body temperature (normothermia, euthermia) is the typical temperature range of humans. The normal human body temperature range is typically reported as 36.5–37.5 °C (97.7–99.5 °F).[8]

Human body temperature varies. It depends on gender, age, time of day, level of exertion, state of health (e.g. illness and menstruation), which part of the body is measured, state of consciousness (wake, sleep, calm) and emotions. Body temperature is maintained within the normal range by thermoregulation, which triggers the central nervous system to adjust temperature.

Measurement methods [ edit ]

Taking a person’s temperature is a first part of a full clinical examination. There are several types of medical thermometers, as well as measuring sites, including:

In the rectum (rectal temperature)

In the mouth (oral temperature)

Under the arm (axillary temperature)

In the ear (eardrum temperature)

On the skin of the forehead over the temporal artery

Use of heat flow sensors

Variations[edit]

37.5°C from 10:00 a.m. to 6:00 p.m., falling to about 36.4°C from 2:00 a.m. to 6:00 a.m. (Based on figure in entry for “Animal Heat” on pages 11-18 :00 p.m. and falls to about 2:00 a.m. to 6:00 a.m. (Based on the figure in the entry for “Beastly Heat” in the 11th edition of the Encyclopædia Britannica, 1910)

Temperature control (thermoregulation) is part of a homeostatic mechanism that keeps the organism at its optimal operating temperature, since temperature affects the rate of chemical reactions. In humans, the average internal temperature is generally believed to be 37 °C (98.6 °F), a “normal” temperature established in the 19th century. But recent studies show that the average indoor temperature for both men and women is 36.4°C (97.5°F). [9] No one has exactly the same temperature at all times of the day. Temperatures periodically fluctuate up and down throughout the day as controlled by the person’s circadian rhythm. The lowest temperature occurs about two hours before the person normally wakes up. Also, temperatures change based on activity and external factors.[10][unreliable medical source?]

In addition to fluctuations throughout the day, normal body temperature can also vary by as much as 0.5°C (0.9°F) from one day to the next, so the highest or lowest temperatures in a day do not always correspond exactly to those highest or match lowest temperatures the next day.

The normal human body temperature varies slightly from person to person and depending on the time of day. Consequently, any type of measurement has a range of normal temperatures. The range for normal human body temperatures, measured orally, is 36.8 ± 0.5 °C (98.2 ± 0.9 °F).[11] This means that any oral temperature between 36.3 and 37.3 °C (97.3 and 99.1 °F) is probably normal.

The normal human body temperature is often given as 36.5–37.5 °C (97.7–99.5 °F).[8] In adults, a literature review found a broader range of 33.2–38.2 °C (91.8–100.8 °F) for normal temperatures, depending on gender and location measured.[12]

The reported values ​​vary depending on the measurement method: oral (under the tongue): 36.8 ± 0.4 °C (98.2 ± 0.72 °F),[13] internal (rectal, vaginal): 37.0 ° C (98.6 °F).[ 13] A rectal or vaginal measurement, taken directly in the body cavity, is typically slightly higher than an oral measurement, and an oral measurement is slightly higher than a skin measurement. Other locations, such as under the arm or in the ear, produce different typical temperatures.[13] While some people consider these averages to be normal or ideal measurements, a wide range of temperatures has been found in healthy people.[5] The body temperature of a healthy person varies by about 0.5°C (0.9°F) throughout the day, with lower temperatures in the morning and higher temperatures in the late afternoon and evening as the body’s needs and activities change.[13 ] Other circumstances also affect body temperature. A person’s core temperature tends to be at its lowest during the second half of the sleep cycle; The lowest point, called the nadir, is one of the primary markers for circadian rhythms. Body temperature also changes when a person is hungry, sleepy, sick, or cold.

Natural Rhythms[ edit ]

Body temperature normally varies throughout the day according to circadian rhythms, with the lowest values ​​at 4 a.m. and the highest in the late afternoon between 4 p.m. and 6 p.m. (assuming the person sleeps at night and stays awake during the day).[11][13] Therefore, strictly speaking, an oral temperature of 37.3 °C (99.1 °F) would be a normal, healthy temperature in the afternoon, but not in the early morning.[13] A person’s body temperature typically changes by about 0.5 °C (0.9 °F) between their highest and lowest points each day.[13]

Body temperature is sensitive to many hormones, so women have a temperature rhythm that varies with the menstrual cycle, called the circummensal rhythm.[10] A woman’s basal body temperature rises sharply after ovulation because estrogen production decreases and progesterone increases. Fertility awareness programs use this change to determine when a woman has ovulated in order to achieve or avoid pregnancy. During the luteal phase of the menstrual cycle, both the trough and average temperatures are slightly higher than in other parts of the cycle. However, the rise in temperature each day is a little lower than usual, so the highest temperature of the day is not much higher than usual.[14][unreliable medical source?] Hormonal contraceptives both suppress the circamensal rhythm and increase typical body temperature by about 0.6°C (1.1°F).[10]

The temperature can also vary throughout the year with the change of seasons. This pattern is called the circannual rhythm.[14] Studies on seasonal variations have produced conflicting results. People living in different climates can have different seasonal patterns. [citation required]

Increased physical fitness increases the magnitude of diurnal temperature fluctuations.[14]

Both average body temperature and the magnitude of diurnal variations in body temperature tend to decrease with age.[14] Elderly patients may have a reduced ability to generate body heat during a fever, so even a slightly elevated temperature can indicate a serious underlying cause in geriatrics. One study suggests that average body temperature has also fallen since the 1850s.[15] The authors of the study believe that the most likely explanation for the change is a population-level reduction in inflammation due to fewer chronic infections and improved hygiene.[16]

Measurement methods [ edit ]

Temperature by measurement technique[12] Method Female Male Oral 33.2–38.1 °C (91.8–100.6 °F) 35.7–37.7 °C (96.3–99.9 °F) Rectal 36.8-37.1°C (98.2-98.8°F) 36.7-37.5°C (98.1-99.5°F) Eardrum 35.7-37.8° C (96.3 – 100.0°F) 35.5 – 37.8°C (95.9 – 100.0°F)

Different methods of measuring temperature produce different results. The temperature measurement depends on which part of the body is measured. The typical daily temperatures in healthy adults are as follows:

The temperature in the anus (rectum/rectal), vagina, or ear (eardrum) is approximately 37.5 °C (99.5 °F) [17] [medical citation required]

The temperature in the mouth (oral) is about 36.8 °C (98.2 °F) [11]

The temperature under the arm (armpit) is about 36.5 °C (97.7 °F) [17] [medical citation needed]

In general, oral, rectal, bowel, and core body temperatures correlate well, although they are slightly different.

Mouth temperature is affected by drinking, chewing, smoking, and open-mouth breathing. Mouth breathing, cold drinks or food reduce oral temperature; Hot drinks, hot food, chewing, and smoking increase oral temperature.[10]

Each measurement method also has different normal ranges depending on gender.[12]

Infrared thermometer[ edit ]

As of 2016, reviews of infrared thermometers have found them to be of variable accuracy.[18] These include tympanic infrared thermometers in children.[19]

Deviations due to external factors[ edit ]

Sleep disorders also affect temperatures. Normally, body temperature drops significantly at normal bedtime and throughout the night. Short-term sleep deprivation results in a higher-than-normal temperature at night, but long-term sleep deprivation appears to lower temperatures.[10] Insomnia and poor sleep quality are associated with a smaller and later drop in body temperature.[10] Likewise, waking up unusually early, sleeping late, jet lag, and changes in shift work schedules can affect body temperature.[10]

Concept [ edit ]

fever [edit]

A temperature set point is the level at which the body tries to maintain its temperature. If the set point is increased, the result is fever. Most fevers are caused by infectious diseases and can be brought down with antipyretics if desired.

An early morning temperature above 37.2 °C (99.0 °F) or a late afternoon temperature above 37.7 °C (99.9 °F) is usually considered a fever, provided the temperature is due to a change in hypothalamic set point. [13] Lower thresholds are sometimes appropriate for older people.[13] The normal diurnal temperature range is typically 0.5°C (0.90°F), but can be greater in people recovering from fever.[13]

An organism with optimal temperature is considered afebrile or apyrexic, meaning “without fever”. If the temperature is increased but the set point is not increased, then the result is hyperthermia.

Hyperthermia[ edit ]

Hyperthermia occurs when the body produces or absorbs more heat than it can release. It is usually caused by prolonged exposure to high temperatures. The body’s thermoregulatory mechanisms eventually become overwhelmed and unable to deal with the heat effectively, causing body temperature to rise uncontrollably. Hyperthermia at or above about 40°C (104°F) is a life-threatening medical emergency that requires immediate treatment. Common symptoms are headache, confusion and fatigue. If sweating has caused dehydration, the affected person may have dry, flushed skin.

In a medical setting, mild hyperthermia is commonly referred to as heat exhaustion or heat exhaustion; severe hyperthermia is called heat stroke. Heat stroke can come on suddenly but usually follows the untreated milder stages. The treatment involves cooling and rehydrating the body; antipyretic drugs are useless for this condition. This can be accomplished by moving out of direct sunlight to a cooler and shady environment, drinking water, removing clothing that might retain heat, or sitting in front of a fan. A bath in lukewarm or cold water, or even just washing your face and other exposed areas of skin, may help.

In fever, the body’s core temperature rises to a higher temperature through the action of the part of the brain that controls body temperature; in hyperthermia, the body temperature is raised without affecting the heat control centers.

hypothermia [edit]

In hypothermia, the body temperature falls below the temperature required for normal metabolism and bodily functions. In humans, this is usually due to overexposure to cold air or water, but can be intentionally induced as a medical treatment. Symptoms usually appear when core body temperature falls 1 to 2 °C (1.8 to 3.6 °F) below normal.

basal body temperature [edit]

Basal body temperature is the lowest temperature the body reaches at rest (usually during sleep). It is generally taken immediately after waking up and before any physical activity, although the temperature measured at this point is slightly higher than the true basal body temperature. In women, temperature differs at different points in the menstrual cycle, which can be used to track ovulation over the long term, both to aid conception and to avoid pregnancy. This process is called fertility awareness.

core temperature[ edit ]

Core temperature, also called body core temperature, is the operating temperature of an organism, especially in deep structures of the body like the liver, compared to temperatures of peripheral tissues. The core temperature is usually kept within a narrow range to allow essential enzymatic reactions to occur. Significant elevation of core temperature (hyperthermia) or depression (hypothermia) for more than a short period of time is incompatible with human life.

Taking temperature inside the heart with a catheter is the traditional gold standard for determining core temperature (oral temperature is affected by hot or cold beverages, changes in ambient temperature, and mouth breathing). Because catheters are highly invasive, rectal measurements are the generally accepted alternative to measuring core body temperature. The rectal temperature is expected to be approximately 1 degree Fahrenheit (or 0.55 degrees Celsius) higher than an oral temperature taken in the same person at the same time. Ear thermometers measure the temperature of the eardrum using infrared sensors, and also aim to measure core body temperature, since this membrane’s blood supply is shared directly with the brain. However, this method of measuring body temperature is not as accurate as rectal measurement and has low sensitivity to fever, with three or four out of ten fever measurements in children being missed.[20] Ear temperature measurement can be acceptable for observing trends in body temperature, but is less useful for positively identifying and diagnosing a fever.

Until recently, direct measurement of core body temperature required either an ingestible device or the surgical insertion of a probe. Therefore, various indirect methods have generally been used as a preferred alternative to these more accurate, albeit more invasive, methods. Rectal or vaginal temperature is generally considered the most accurate determination of core body temperature, particularly in hypothermic conditions. In the early 2000s, ingestible thermistors were manufactured in encapsulated form that allowed the temperature in the digestive tract to be transmitted to an external receiver. One study found that these were comparable in accuracy to rectal temperature measurement.[21] A new method using heat flow sensors has recently been developed. Several research papers show that its accuracy is similar to invasive methods.[22][23][24]

Temperature fluctuation[ edit ]

hot [edit]

44°C (111.2°F) or greater – Death almost certainly occurs; However, humans have been known to survive up to 46.5 °C (115.7 °F). [25] [26]

43°C (109.4°F) – Usually death or severe brain damage, persistent convulsions, and shock. Cardio-respiratory collapse is likely to occur.

42°C (107.6°F) – Subject may turn pale or remain flushed and flushed. They may become comatose, become severely delirious, vomit, and convulsions may occur.

41°C (105.8°F) – (Medical Emergency) – Fainting, vomiting, severe headache, dizziness, confusion, hallucinations, delirium and lightheadedness may occur. Heart palpitations and shortness of breath can also occur.

40°C (104°F) – Fainting, dehydration, weakness, vomiting, headache, shortness of breath and dizziness may occur, as well as profuse sweating.

39°C (102.2°F) – Profuse sweating, flushed and flushed. Rapid heart rate and shortness of breath. This can be accompanied by exhaustion. Children and people with epilepsy may experience convulsions at this temperature.

38°C (100.4°F) – (Classified as hyperthermia if not caused by fever) – Flushing, sweating, feeling thirsty, severe malaise, mild hunger. If this is caused by a fever, chills may also occur.

Normal [edit]

36.5–37.6 °C (97.7–99.7 °F) is a typically reported range for normal body temperature.[8]

cold [edit]

36°C (96.8°F) – Feeling cold, mild to moderate tremors. Body temperature can drop so low during sleep. This can be a normal body temperature for sleeping.

35°C (95°F) – (Hypothermia is below 35°C (95°F)) – Intense shaking, numbness and bluish/grey skin. There is a possibility of cardiac irritability.

34°C (93.2°F) – Severe shaking, loss of motion of fingers, blueness and confusion. Some behavioral changes may take place.

33°C (91.4°F) – Moderate to severe confusion, drowsiness, decreased reflexes, progressive loss of tremor, slow heartbeat, shallow breathing. The shaking can stop. The subject is unresponsive to certain stimuli.

32°C (89.6°F) – (Medical Emergency) – Hallucinations, delirium, complete confusion, extreme drowsiness progressing to coma. Trembling is absent (subject may even think it is hot). The reflex may be absent or very slight.

31 °C (87.8 °F) – Coma, very rarely conscious. No or slight reflexes. Very shallow breathing and slow heartbeat. Possibility of serious cardiac arrhythmias.

28°C (82.4°F) – Serious cardiac arrhythmia is likely and breathing may stop at any time. The person appears to be dead. [citation required]

24–26 °C (75.2–78.8 °F) or less – Death usually occurs from irregular heartbeat or respiratory arrest; However, some patients have been known to survive with body temperatures as low as 13.7 °C (56.7 °F). [27]

There are non-verbal physical cues that can indicate that a person has a low body temperature that can be used for those with dysphasia or infants.[28] Examples of non-verbal cues to cold include silence and lethargy in relation to kinesiological movements, sneezing, unusual pallor of the skin in Caucasians, and in males, shrinkage and contraction of the scrotum.[29]

Historical understanding[edit]

In the 19th century, “blood heat” was reported as 98°F in most books until a study published the mean (but not the variance) of a large sample as 36.88°C (98.38°F).[30] Subsequently, this mean was widely reported as “37 °C or 98.4 °F” [31][32] until editors determined that 37 °C equaled 98.6 °F and not 98.4 °F. The value of 37 °C was established by the German physician Carl Reinhold August Wunderlich in his 1868 book[33] which brought temperature charts into widespread clinical use.[34] Dictionaries and other sources [which?] citing these averages added the word “approximately” to show that there is some variation, but generally did not specify how large the variation is. [citation required]