Tuesday, July 19, 2011

Q&A 2: Humidity

TIme for another Q&A. This one comes from my grandmother, asking “What is the difference between humidity and dew point?” Given our current weather throughout the nation, this is a good question.

We have been hearing lately about how the humidity is high or the dew point is tropical. Temperature is simply how warm or cold the air. On a more technical level, it is the average kinetic energy of what is being measured.

Dew point is simply what temperature air can cool to before it gets saturated and either the water in the air needs to be removed via condensation or rain. The dew point tells us how much water is already in the air. It is measured by finding what temperature water is in the air. Once the dew point pasts 70, it is considered to be tropical. Temperature can never be below the dew point.

Humidity is the percentage of water in the air compared to the temperature. When the humidity hits 100%, the air can handle no more water, so it condenses out, which can cause rain, or droplets on glass to form. When the humidity is high, water evaporates more slowly, which is why when the humidity is high its harder to cool yourself.

The body uses sweat to keep cool because evaporation is a heat absorbing process, so when it is humid, the body cannot cool itself, so you start to overheat. This is why high humidity and hot temperatures are dangerous. It is also why it is good to invest in dehumidifiers. Dehumidifiers remove the water from the air, so that more water can be evaporated, helping to cool you. This is also why a house at 75° in the winter feels nicer than outside at 75° in the summer...less humidity.

From the guy with his eye on the sky, Travis...the camping lifeguard

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