What in the world is ‘corn sweat’ and is it really causing this heat wave?
<![CDATA[By Angela Fritz People are all about corn sweat today. No, I’m not making this up. Our readers are concerned that “corn sweat” is causing this week’s heat wave, and they are confused. But after tracking down the source of the produce-laden perspiration, I am here to allay the apprehension. Yes, it’s going to be really hot in the central United States this week. High pressure will build over it this week, and humidity is on the rise. The National Weather Service issued an excessive heat watch for parts of the Upper Midwest, where actual temperatures are expected to climb into the 90s on Thursday, and the heat index will “easily exceed 100 degrees.” In covering this heat wave, CNN wrote that there’s a dangerous heat dome forming over the United States, and “corn sweat could be to blame.”
@capitalweather Is it true we are under a heat dome because of corn sweat? News ticker just said so on CNN.— VACountryLife (@VACountryLife) July 18, 2016
[Is a ‘dry heat’ actually better?]In regions where there are vast swaths of any plant, corn in particular, humidity can be notably higher than it otherwise would be. And the Midwest is covered in corn. Over 94 million acres of corn was planted in 2016, the USDA reported last month, up 7 percent from 2015 and the third-highest corn acreage in the United States since 1944. exceed 85 degrees during extreme heat waves, leading to a heat index of 134 degrees. These high-humidity events have been linked to evapotranspiration, along with wet springs and flooding in days prior. The other interesting thing we have to remember about higher humidity is that it actually limits how hot the temperature can get. When the sun beats down on the ground, two things can happen: All of the sun’s energy can be used to heat up the ground, or some of it can be used to evaporate the moisture in the ground. Evaporation takes heat to accomplish, which is why it’s a cooling process. It also means that not as much of the sun’s energy is spent heating up the ground. This is why the hottest temperatures on Earth are recorded in deserts, like the Middle East, the Sahara and the Mojave— there’s very, very little moisture to be evaporated. The world record for hottest temperature, 134 degrees, was set in Death Valley in 1913. You’ll never see any place that is even remotely humid hit a temperature that high. This article appeared on The Washington Post website at https://www.washingtonpost.com/news/capital-weather-gang/wp/2016/07/18/what-in-the-world-is-corn-sweat-and-is-it-really-causing-this-heat-wave/?hpid=hp_hp-more-top-stories-2_cwg-cornsweat-134pm%3Ahomepage%2Fstory]]>