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Measuring weather
Surface observations - temperature
When we want to determine how hot or cold the air is, we measure its temperature. Temperature is a measure of the energy that molecules have, specifically its kinetic energy. So since temperature is a measure of air molecule speed, when you feel warmer air, you are really feeling faster molecules colliding with your skin more frequently than would happen in cold air.
We often imagine the common liquid-in-glass thermometer when thinking about measuring temperature. When the air surrounding the thermometer warms, its molecules move faster, striking the reservoir bulb more frequently, and transferring more energy to the liquid. As the liquid warms, it expands, moving up the glass tube to larger temperature values. The process of making accurate, standardized temperature records dates back nearly 2000 years. Early thermometers, called thermoscopes, relied on temperature changes to move colored water exposed to air up and down a tube. They looked much like a mercury barometer. Later versions used sealed liquids, such as alcohol, mercury, or even wine, but the greatest advancement was scaling the measurements to a fixed point, such as the freezing point of water or a well-mixed solution of saltwater and ice. Today, such standardization to a constant is key for the scientific reporting of the temperature as a number. Most commonly, this is done in one of three scales:
Links and resources
Surface observations - temperature
When we want to determine how hot or cold the air is, we measure its temperature. Temperature is a measure of the energy that molecules have, specifically its kinetic energy. So since temperature is a measure of air molecule speed, when you feel warmer air, you are really feeling faster molecules colliding with your skin more frequently than would happen in cold air.
We often imagine the common liquid-in-glass thermometer when thinking about measuring temperature. When the air surrounding the thermometer warms, its molecules move faster, striking the reservoir bulb more frequently, and transferring more energy to the liquid. As the liquid warms, it expands, moving up the glass tube to larger temperature values. The process of making accurate, standardized temperature records dates back nearly 2000 years. Early thermometers, called thermoscopes, relied on temperature changes to move colored water exposed to air up and down a tube. They looked much like a mercury barometer. Later versions used sealed liquids, such as alcohol, mercury, or even wine, but the greatest advancement was scaling the measurements to a fixed point, such as the freezing point of water or a well-mixed solution of saltwater and ice. Today, such standardization to a constant is key for the scientific reporting of the temperature as a number. Most commonly, this is done in one of three scales:
- Fahrenheit - used most often in the United States
- Celsius - used in most other parts of the world
- Kelvin - used mainly in science
Links and resources
