Have you ever visited a place that just made you feel hot and sticky the entire time, no matter what you did to cool off? You can thank humidity for that unpleasant feeling.

Humidity is the amount of water vapor in the air. If there is a lot of water vapor in the air, the humidity will be high. The higher the humidity, the wetter it feels outside.

On the weather reports, humidity is usually explained as relative humidity. Relative humidity is the amount of water vapor actually in the air, expressed as a percentage of the maximum amount of water vapor the air can hold at the same temperature. Think of the air at a chilly -10 degrees Celsius (14 degrees Fahrenheit). At that temperature, the air can hold, at most, 2.2 grams of water per cubic meter. So if there are 2.2 grams of water per cubic meter when its -10 degrees Celsius outside, we're at an uncomfortable 100 percent relative humidity. If there was 1.1 grams of water in the air at -10 degrees Celsius, we're at 50 percent relative humidity.

When humidity is high, the air is so clogged with water vapor that there isnt room for much else. If you sweat when its humid, it can be hard to cool off because your sweat cant evaporate into the air like it needs to.

Humidity is blamed for all kinds of negative things, including mold in your house (usually the bathroom, where its wet a lot of the time), as well as malfunctions in regular household electronics. Moisture from humid air settles, or condenses, on electronics. This can interrupt the electric current, causing a loss of power. Computers and television sets can lose power like this if not protected from the effects of humidity. Living with humidity is easier with the aid of a dehumidifier, which sucks moisture out of the air.

High humidity is also associated with hurricanes. Air with high moisture content is necessary for a hurricane to develop. U.S. states such as Texas and Louisiana, which border the very warm Gulf of Mexico, have humid climates. This results in tons of rainfall, lots of flooding and the occasional hurricane.

Tropical waterfalls are humid places.

The Not-So-Hot Zone
People are usually comfortable at 45-percent relative humidity.


all weather conditions for a given location over a period of time.


device that pulls moisture from the air.


to change from a liquid to a gas or vapor.


overflow of a body of water onto land.


amount of water vapor in the air.


tropical storm with wind speeds of at least 119 kilometers (74 miles) per hour. Hurricanes are the same thing as typhoons, but usually located in the Atlantic Ocean region.


to not work correctly.




hollow structure used to give form to a liquid substance as it hardens.


amount of precipitation that falls in a specific area during a specific time.

relative humidity

ratio between the amount of water vapor in the air and the air's saturation point. Relative humidity is expressed as a percentage.


visible liquid suspended in the air, such as fog.