– dew point. I know over 65 dew point is gross. But why?
In: Chemistry
All ambient air has some amount of evaporated water in it. The amount of water vapor it can hold varies based on temperature and pressure, and warmer air can hold more water vapor. “Humidity” is referring to the percentage of water vapor the air at its current temperature and pressure can hold, so 100% humidity means that water basically stops evaporating because it can’t hold any more water.
The dew point is the temperature air needs to cool to (assuming constant pressure) to achieve a relative humidity of 100%. If it cools any more water will be forced out of the air in the form of condensation or precipitation. It is generally miserable to be in 100% humidity because you can’t sweat and you will just feel moist all over.
The basic concept is that there is water in the air, but the air can only hold so much water. Specifically, the amount of water the air can hold depends a lot on temperature, the higher tempeature the more water it can hold. This means that if you cool the air down it might not be able to hold the water anymore. The temperature at which that happens for the air we are speaking of, is called the dew point.
Anyway we use sweat that evaporates to cool us, so if its humid and hot, we will sweat a lot, but that sweat isn’t evaporating because the water is having a hard time holding on to the water. So the attempt to cool yourself doesn’t work and the body just continues to sweat more.
Dew point is a measure of the moisture content of air. Dew point of 65F means that water will begin to condense out of air at an actual temperature of 65F. Relationship between absolute humidity and dew point is not linear – a 80F dew point contains much more water than 65F.
Dew point has an influence on sweating/efficiency of sweating. Higher dew points makes it more difficult for sweat to evaporate – and it’s the evaporation that cools humans off. High dew points are correlated with overheating and more heat stress.
The Dew Point is the temperature in which water stops evaporating and starts condensing.
Once the Dew Point passes 65, it starts getting close to the resting temperature of your skin (which can be much lower than our core temp). The closer to the Dew Point your skin temp is, the longer it takes water to evaporate. Since evaporation reduces temperature and removes water, high dew points will feel warmer and more swampy.
Dew point just means the temperature when water comes out of the air and becomes a liquid. Dry air needs to be cooler and more water content condensed at higher temperatures. 65 is a pretty humid dew point, so when it’s hot it’ll be terrible because that humid air transfers heat much faster than dry air so it feels even hotter.
You will get a cloud layer where dewpoint and temperature meet which is cool for knowing the approximate heights of clouds.
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