Why Does a Hot Day Feel Hot?

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Did you know that it's not just high temperatures that makes us feel hot on sunny days in the summer? 

Normal skin temperature for an adult ranges between 33 °C and 37 °C. Our bodies are cooled naturally by perspiration that's released from pores in the skin. When sweat evaporates, it carries away heat from the body, reducing skin temperature. Capillaries in the surface layers of the skin also help with cooling by circulating blood, which also loses heat to the ambient air. Anything that interferes with this process changes the perception of how hot or cold it is at any one time. So higher humidity reduces the rate at which perspiration evaporates, making it feel clammy and warmer. A less humid day doesn't feel as warm, even though the temperature may be the same. Air movement also increases the rate of heat loss from the skin. So a windy day feels colder than a day when the air is still. The air blown out of a room fan feels cold. Fans don't actively cool air (air conditioners do) The air they circulate is at the same temperature as the air in the rest of a room. They simply remove air that has been in contact with skin and has absorbed heat from it. They do this continuously so new air is always moved into contact with the skin. Since this "new" air is at room temperature and not warmed, heat flows at a faster rate from skin. The reason for the greater rate of heat transfer is because heat flows from a region of hot temperature to one at a lower temperature. The greater the difference in temperature, the higher the rate of heat flux. And so this cools our bodies faster than natural cooling. Blowing on hot soup in a spoon does the same thing.