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What Is Wind Chill?

Thermal sensation is a measure of the sensation of cold or heat that humans find in cold air with a lot of wind or hot air with the sun, without wind and high humidity. This part is about the cold wind, the additional feeling of cold due to the wind.

What is wind chill?

The phenomenon of thermal sensation, or cold wind, is, therefore, a phenomenon in which you feel much colder with the wind than without the wind. The colder it is and the faster the wind blows, the colder it feels. We can express that heat loss in a kind of emotional value of temperature.

At a feeling temperature below -10 degrees Celsius, symptoms of hypothermia may appear after several hours. Sensory temperatures below -15 degrees Celsius can cause cold injury after one hour. Temperatures below -20 degrees there is already a slight chance of freezing after half an hour, even with well-sealed winter clothing.

Under extreme weather conditions, sensation temperatures have occurred in the Netherlands from -23 degrees in the south to -28 degrees in the north of the country (January 14, 1987).

The risk of freezing symptoms increases faster at a wind temperature below -25 degrees.

What Influence Does Sweat Have on the Thermal Sensation?

The human body is cooled by air when the air is colder than body temperature. The body can also be cooled by evaporation of moisture (usually  sweat ). As the temperature increases, more moisture needs to be evaporated and if it is warmer than body temperature, this is the only option. This explains why sweating at high temperatures requires more fluid to be replenished by drinking.

As a result, the air layer on the skin heats up and  contains  more  water vapor . This makes further cooling more difficult. If the air layer is blown out, by a  fan,  or by the wind, it will also feel colder, although the thermometer will still show the same temperature. However, we can  measure  the  temperature of  the wet bulb .

This is somewhat comparable to wind cooling in the case of high temperatures, because evaporation plays a role here. However, in the case of low temperatures, the thermal sensation is determined by the  convection  of the air film around the skin and the associated heat dissipation.

Does the Sensation of Temperature Also Affect Inanimate Objects?

The term thermal sensation does not apply to inanimate objects such as machinery, car antifreeze, or mercury. For example, at an outside temperature of 5 ° C and wind force 7, the wind temperature is -2 ° C, but the water will not freeze. Therefore, we cannot measure the thermal sensation with a thermometer.

Wind influences the rate at which cooling occurs: water pipes and heating elements freeze faster if the wind blows hard during frost.

Wind also affects heat transfer around buildings. It has been shown that heating fuel consumption in strong winds can be doubled in homes. When determining the insulation value of existing buildings, detection temperatures must be taken into account.

What Is Thermal Temperature?

Thermal temperature is the absolute measure of temperature and is one of the main parameters of thermodynamics. Its unit of measurement in the international system of measurements is the kelvin.

This is an "absolute" scale because it is the measure of the fundamental property of temperature: its zero value, or absolute zero, is the lowest possible temperature. There is nothing that can have a temperature below absolute zero. The absolute zero of the thermodynamic temperature, transformed on the Celsius scale, would be equivalent to 273.5ºC. This characteristic is defined by the third law of thermodynamics in which theoretically no element can have a temperature below 0 K.

The person in charge of defining the absolute temperature scale was the British physicist and mathematician William Thomson, who later became Lord Kelvin.

The temperature of a body at rest is a measure of the average of the kinetic energy of the movements of translation, vibration, and rotation of the components of matter particles, such as molecules, atoms, and subatomic particles (neutrons, protons, and electrons). ).

The complete variety of these kinetic movements, together with the potential energies of the particles and also, occasionally, other types of energy of the particles in equilibrium with them, constitute the total internal energy of a substance. Internal energy is also loosely called heat energy or heat energy in the conditions when there is no work.

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Published: August 28, 2017
Last review: March 16, 2020