# Calculating the Heat Index

METEOROLOGIST STEVE FRAZIER @FRAZIERFOX9

The actual air temperature here in the Upper Midwest can vary greatly throughout the year. The biggest bite comes in the winter when we commonly see the wind and cold getting together and adding insult to injury. The summer season is less brutal but it can still sting from time to time.

THE HEAT INDEX

The Heat Index is a meteorological method of calculating how elevated heat and humidity can affect the human body. Evaporation is a powerful thing and leads to some big time cooling. That gust of cool fresh air from a thunderstorm, that chill you get in a breeze and that phrase, “It’s a dry heat”, all stem from how much moisture is in the air. The body cools itself through the process of evaporation. The process of evaporation is most efficient when the air is drier. Dry air is not hard to come by here in Minnesota as our air masses usually originate across the plains of Canada and not from the ocean. However, in the summertime, the Upper Midwest gets a few doses of air from the Gulf of Mexico.

CALCULATING THE HEAT INDEX

Thanks to science, and believe me, its very scientific, there is a way of calculating just how hot you will feel when the humidity increases.  The simple way to determine this is to just plug in the temperature and dewpoint into a formula to get your “Feels Like” temperature. You can find that formula by clicking on this link http://www.wpc.ncep.noaa.gov/html/heatindex.shtml  courtesy of The National Weather Service.

The actual formula that is crunched to reach this apparent temperature is quite complex. However, some of you may want to do the calculations and for those people, here is the link to the formula. http://www.wpc.ncep.noaa.gov/html/heatindex_equation.shtml . Have fun plugging and chugging with that mathematical madness.

Check out the link on heat safety from the National Weather Service and stay cool everyone! http://www.nws.noaa.gov/os/heat/

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