I was reading an article on Japan’s weather for the Olympic being so hot and the author said “with a dew point of 72 degrees what do you expect?”.
I don’t know what to expect!
In: Chemistry
The dew point is one way of measuring the absolute amount of moisture in the air.
The amount of moisture than air *can* hold is greatly dependent on temperature. At 50 F, air can have up to 1.21% water vapor. At 68 F, air can have up to 2.31% water vapor. At 77 F, air can hold up to 3.13% water vapor.
So, if you take the percent of water vapor in the air and then map it to the temperature where that amount is the maximum (or “saturated”). It is called the dew point because when when the temperature of the air is the same as its dew point, then air is “full” of water and dew will often form on the grass.
Two things about dew points. First, higher dewpoints simply means air with more moisture in it. Second, when the dewpoint and the temperature are close, then the *relative* humidity is high. That means that dew might form, fog might form, sweat will have trouble evaporating. So a dewpoint of 40 F means different things when the temperature is 40 F (a cold misty day) or when the temperature is 90 F (dry day because the air is .8% water when it *could* have 4.8% water) even though it is the same *absolute* amount of water in the air.
This stuff is complicated. Let it sink in for a while.
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