Heat index it's a measurement of how hot it really feels outside, considering both air temperature and relative humidity.

The temperature outside feels hotter as humidity rises. This happens because in a dry environment our bodies are able to cool themselves better. When it gets hot on a dry summer day, our bodies produce sweat. That sweat captures the heat energy and evaporates, taking the heat with it. Conversely, as you sweat on a humid day, the sweat cannot evaporate as much because there is already moisture in the air, and therefore less heat energy is transferred off your body and into the air.

National weather service considers it a dangerous number when the index starts to reach 100° F. Heat index of 105° F or more, lasting for two or more days, is considered as dangerous and prompts an "excessive heat warning" from the weather service.

On July 8th 2003 a record heat index was recorded in Saudi Arabia, with a temperature of 178 degrees (81°C).

Note, it's important to remember that heat-index-temperature is not the same as an actual temperate. Refer to "What is heat index" for explanation of how heat index is measured.

Wet bulb globe temperature (WBGT) is a measurement of heat stress in a direct sunlight. This includes a number of factors: ambient temperature, wind speed, humidity, sun angle, cloud cover, solar radiation. f you work or exercise in direct sunlight, this is a good measure to monitor. The American College of Sports Medicine set down the basic guideline that any temperature where WBGT value is over 82°F (28°C) is not appropriate for competitions and sport practice.

There are three ways to measure how hot it is: temperature, heat index (which also take the relative humidity into account), and the Wet Bulb Global Temperature (which also takes into account wind speed and solar radiation).

Your car is the hottest place on Earth.Sun's radiation can heat up objects inside the car, like dashboard and seats. Those objects then emit their own heat (radiation), which is not efficient at escaping the car back through the windows as it was at entering the car, thus heating the car like a greenhouse.

There is a distinction to make between fever, when you get sick, and hyperthermia.

When you get sick and get a fever, that is your brain telling your body to heat up in order to increase the function of your immune system. This process is controlled by the hypothalamus in your brain. In medicine, this fever is defined from a temperature of 38°C. Fever is a reaction of thermoregulation.

On the other hand, hyperthermia occurs when environmental variables are responsible for raising your body's temperature, and the body cannot keep up and cool itself in time, thus overheating.

Once you become hypothermic, you get fast pulse, low blood pressure, extreme weakness, dizziness, vomiting, and diarrhea which can progress to heat stroke. The stroke brings neurologic problems like confusion and seizures (at 104° Farheneit). If the temperature isn't reduced at that stage, irreversible damage can occur.

Body's enzymes are designed to be active at specific temperature ranges. If the body gets too hot, enzymes stop working and cells die. Kidney, lungs and nervous systems stop to function. At that point, a person can die very quickly if not cooled down immediately.

Absolutely not. Very young and very old people should take precautions to stay cool. Nevertheless, young and healthy people don't know the danger of heat, and some think that exercising on really hot days will somehow make them healthy. It is not. Even great athletes can die exercising on a hot days too, going from perfectly healthy to dead in a matter of hours.

Yes it can, but it takes some time, and the duration is variable for each individual. To be better at heat management, the body needs to increase its blood and plasma volume, which enables the body to get better at retaining salt. Better salt retention enables the body to hold on to more fluid, and more fluid leads to more sweat, facilitating heat loss in the process.

Undress and rapidly cool the person, which means pack them with ice, especially around armpits, neck and growing; spray them with tepid water to help evaporate the heat off the skin.

There is no perfect answer to this question. Depending on their health, a person might be able to tolerate elevated temperatures (~107°F) for some time, but an extremely hot internal temperature (120° Fahrenheit) will destroy cells and kill a person in less than 5 minutes.

The army puts pee on the "do not drink" list because of its salinity, where drinking urine will make you more dehydrated than if you drink nothing at all. However, the urine is sterile, does not have any bacterial (unless you have an infection), it contains electrolytes, some little bit of hormones, and mostly water!

The more hydrated you are, the more water (vs salt) there is in your pee. So, in extreme situation, if you know you are about to run out of water, you could save your pee and drink it early on, while the contents of your pee are still predominantly water.