Zach’s Weather Whys: Humidity

Zach's Weather Whys

PEORIA, Ill. — Whether you describe it as sticky or muggy, humidity plays a big role in our summer here in Central Illinois.

Humidity can be categorized in levels from pleasant, all the way to miserable. It depends on the dew point, which is the temperature the air needs to drop to become saturated. The air is considered pleasant when dew points are lower than 55 degrees.

As the dewpoint increases, the air gradually gets more uncomfortable. Anything more than a dew point of 76 is considered oppressive and it does live up to its title.

Some of the highest dew points tend to show up in the Midwest during the afternoons from mid-to-late Summer. The extensive amount of corn and other crops put a lot of extra water vapor into the air which causes the humidity to spike.

According to the U.S. Geological Survey, just one acre of corn sweats off 3,000 – 4,000 gallons of water a day! Corn and other plants transpire through their leaves and that extra water gets evaporated into the air which increases the dew point. The dew point in a corn field can be as much as 5 degrees higher than area that has no crops.

As a result, it feels hotter than it really is, especially when walking through a farm field. High humidity and hot temperatures are a recipe for a sticky summer afternoon. Our bodies evaporate sweat to cool off and higher levels of humidity caused by corn and other crops prevent a lot of that sweat from evaporating and we can’t cool off that easily.

Even if you don’t live near farmland that humid air can still travel far from the source.

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