Overview
Air temperature is a measure of how hot or cold the air is. More specifically, temperature describes the kinetic energy, or energy of motion, of the gases that make up air. As gas molecules move more quickly, air temperature increases.
Influencing Factors
Air temperature is dependent on the amount and strength of the sunlight hitting the earth and atmospheric conditions, such as cloud cover and humidity, which trap heat.
Air pollution affects air temperature by increasing the amount of greenhouse gases in the atmosphere. Greenhouse gases trap heat near the earths surface. For instance, carbon dioxide and carbon monoxide emitted by cars, power plants, and factories, trap heat in the air.
Importance
Air temperature affects the growth and reproduction of plants and animals, with warmer temperatures promoting biological growth. Air temperature also affects nearly all other weather parameters such as the rate of evaporation, relative humidity, wind speed & direction, and precipitation patterns & types.
Measurement
Temperature is usually expressed in degrees Fahrenheit or Celsius. 0 degrees Celsius is equal to 32 degrees Fahrenheit. Degrees Celsius maybe converted to degrees Fahrenheit and vice versa by use of these equations: °C = (5/9) * (°F - 32) and °F = (9/5) * °C + 32.
A more scientific way to describe temperature is in the standard international unit Kelvin. 0 degrees Kelvin is called absolute zero. It is the coldest temperature possible, and is the point at which all molecular motion stops. It is approximately equal to -273 degrees Celsius and -460 degrees Fahrenheit.
Temperature can be measured in numerous ways, including thermistors, thermocouples, and mercury thermometers. Thermistors are metallic devices that undergo predictable changes in resistance in response to changes in temperature. Thermocouples are two metals touching and when heated, create a predictable voltage. The resistance or voltage is measured and then converted to a temperature reading in Celsius, Fahrenheit, or Kelvin. Mercury thermometers use the thermal expansion of Mercury to display temperature changes.