What is Heat Index?


When the summer heat intensifies, all eyes turn to warmth. But for the most part, experts say it’s the heat index that should be of more concern.

While it’s the temperature ending in 10-day forecasts and electronic signs outside the banks, the heat index is often a better indicator of the intensity of the heat and the dangers it may pose to humans.

According to Kimberly McMahon, a meteorologist with the National Weather Service, the heat index is a measure of how hot it really feels outside when humidity and other factors are taken into account along with temperature.

“The heat index is important – and this is especially true for the Northeast – because it includes the amount of moisture or humidity in the air, and that humidity or humidity can make the air temperature feel even higher,” said Ms. McMahon.

In addition to using it to provide a more accurate measurement of how you’re feeling outside, the National Weather Service relies on the heat index to let people know how much heat the human body can handle before it becomes dangerous.

Sometimes, if it’s humid enough, the weather doesn’t have to be that hot outside for it to be harmful.

“With high humidity, it’s harder for the human body to sweat and then evaporate that sweat,” said Ms. McMahon. “With the inability to cool inefficiently, this increases a person’s heat stress.”

For example, on a day when the temperature outside is 92 degrees and the humidity is 70 percent, the heat index is 112 degrees. When the heat index reaches this level it is dangerous and can cause sunstroke, muscle cramps and heat exhaustion. Heat stroke is also a risk for those who do physical activity or stay outside for long enough under these conditions.

The National Weather Service uses heat index values ​​to know when to post heat recommendations, times, and warnings that encourage residents in an area to avoid being outside during the hottest hours of the day.

While other countries use the heat index to measure how hot it is outside, an additional measure used in some countries, such as Saudi Arabia, is wet bulb temperature.

The National Weather Service refers to “Wet Bulb Globe Temperature” as a measure of heat stress under direct sunlight, which affects temperature, humidity, wind speed, cloud coverage, and the angle of the sun.

Weather-related deaths and injuries are often associated with more severe events such as hurricanes and tornadoes, but heat-related illnesses are the leading cause of weather- or environmental-related deaths. American Public Health Association.

More than 600 people across the country die every year due to extreme heat. Centers for Disease Control and Prevention.

McMahon said that regardless of whether the person lives in an area where they are accustomed to the heat, it is important to pay attention to temperature-related clocks and warnings while they are in place.

“Both heats are dangerous, whether it’s high humidity temperatures or the dry heat emanating from the southwest desert,” he said. “People always need to pay attention and take it seriously because it’s the #1 weather killer in the United States.”

The heat index is measured using a multiple regression analysis that uses actual temperature and humidity to produce a number that better represents how warm it feels outside.

The equation is long (-42.379 + 2.04901523T + 10.14333127R – 0.2247541TR – 6.83783 x 10-3T2 – 5.481717 x 10-2R2 + 1.22874 x 10-3T2R + 8.5282 x 10-4TR2 – 1.99 x 10-6T2R2), R represents moisture and T represents temperature.

Since this is a long math problem to do on the fly, the National Oceanic and Atmospheric Administration has a simple graphic that everyone can understand.

According to the chart, on a day when the temperature reaches 106 degrees and the humidity is 50 percent, the heat index is 137 degrees.

Heat index values ​​were created assuming shady conditions with a slight wind, so full exposure to sunlight can make you feel up to 15 degrees warmer, according to the National Weather Service.


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