Why does 100 degrees feel hot

Dry desert heat can be more forgiving because low humidity allows for quick evaporation of sweat—but only if people drink enough water to make up for the loss of body fluids. But people also lose salt when they sweat. And it's not always easy to tell how much your individual body needs to replace the loss. That means that you urinate as often as usual, and the color of urine is normal—a dark hue is a sign of dehydration.

Or put a dash of salt and a teaspoon of sugar in a liter of water," Morocco says. The salt replaces salt lost through sweat, and sugar helps transport salt through the intestinal walls. When people can't drink enough water, dehydration sets in. Blood flow to the skin decreases, along with the ability to sweat. Body heat builds up. A body temperature of degrees indicates danger; degrees is the definition of heat stroke; and a temperature of degrees could result in irreversible organ damage or even death.

A normal, healthy person who is not used to the heat can, in heat wave conditions, sweat as much as 1. Someone acclimated to the hot weather, say a Phoenix telephone lineman, develops the ability to sweat and thus cool off at a more intense rate, losing up to two quarts of sweat in an hour.

High heat and lack of water are prime conditions for multiple organ damage. Internal temperature soars, heart rate goes up, blood flow slows down, and organs begin to shut down. People begin to feel really bad. Other organs begin to shut down, then fail. Under extreme heat conditions, it can all happen very quickly—in an hour or even less.

The brain, too, is affected by reduced blood flow. That's why people in the throes of heat illness begin to make poor, often life-threatening, decisions. The body actually feels cooler in arid conditions. There is direct relationship between the air temperature and relative humidity and the heat index, meaning as the air temperature and relative humidity increase decrease , the heat index increases decreases. Figure 1. Heat index chart. In order to determine the heat index using the chart above, you need to know the air temperature and the relative humidity.

When the relative humidity is low, the apparent temperature can actually be lower than the air temperature. In the Panhandles, we commonly see hot temperatures during the summer, but the low relative humidity values make it somewhat unusual to see dangerous heat index values i.

A full heat index chart for a larger range of temperatures and relative humidity values can be found at this link. Disclaimer Information Quality Help Glossary. News Headlines. Customize Your Weather. Privacy Policy. Heat Index Weather. Current Hazards. Local Radar. Rivers and Lakes. Climate and Past Weather. Heat Index Temperature vs. Humidity How to read the chart: find the temperature on the left hand side, then move to the right until you find the column for the approximate relative humidity.

Or, if you know the temperature and the dewpoint, figure out the heat index and relative humidity RH using this calculator. Follow us on Twitter. Follow us on Facebook. Follow us on YouTube. Disclaimer Information Quality Help Glossary. Air Temperature. Possible heat disorders for people in higher risk groups. Sign Up. Support science journalism. Knowledge awaits. See Subscription Options Already a subscriber? Create Account See Subscription Options.

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