Thread: Silly question about humidity..
08-23-2004, 05:24 AM #1Retired Vet
- Join Date
- Nov 2001
Silly question about humidity..
I'm just home from vacation in the Balearic Islands, anyway it was so da*n humid there but last Thursday night humidity was 96%, what happens if it reaches 100% or is there such a thing?.
08-23-2004, 05:27 AM #2Originally Posted by BOUNCER
08-23-2004, 05:29 AM #3
Air reaches mass saturation point...
08-23-2004, 05:31 AM #4
By Jack Williams, USATODAY.com
Humidity is the amount of water vapor in the air and can be described in different ways.
The term that you'll hear most often to describe the humidity is "relative humidity." This also happens to be, in my opinion, the measurement of humidity that's hardest to understand.
Another common measurement of humidity is the "dew point," which most of us also also have to work, at least a little, to understand.
Unless you are a weather forecaster, or a scientist or engineer involved in work involving the amount of water vapor in the air, you can easily go through life without understanding "relative humidity." On the other hand, it is nice to know what the person on television is taking about when he says "dew point."
These and other terms used to in relation to humidity are defined at the bottom of this page. If after glancing at them, you still don't quite understand what's going on, try going to the USATODAY.com Getting a handle on humidity page.
Why humidity is worth worrying about
The humidity combined with hot temperatures makes the heat more dangerous. (Related: The dangers of heat and humidity)
Indoor, as well as outdoor humidity is important, and humidity that's too high or too low can be dangerous for both you and your house. (Related story: Humidity inside your home)
Humidity is a key player in the weather
The U.S. Geological Survey estimates that the Earth has about 326 million cubic miles of water. This includes all of the water in the oceans, underground and locked up as ice.
Only about 3,100 cubic miles of this water is in the air, mostly as water vapor, but also as clouds or precipitation, at any one time, the Geological Survey estimates.
While this is a small share of Earth's water, our planet would be very different without it. If Earth's air didn't contain as much humidity as it does, our weather would be like that of Mars: No clouds (except dust), no rain, sleet or snow, no thunder and lighting, no fog. And, without all of this water in all of its forms, Earth's life, if there were any at all, but be as hard to find as life on Mars is to find even signs of. (Related: Understanding water in the atmosphere)
Humidity can be less than 100% when it's raining
Humidity is a measure of the amount of water vapor in the air, not the total amount of vapor and liquid. For clouds to form, and rain to start, the air does have to reach 100% relative humidity, but only where the clouds are forming or where the rain is coming from. This normally happens when the air rises and cools. Often, rain will be falling from clouds where the humidity is 100% into air with a lower humidity. Some water from the rain evaporates into the air it's falling through, increasing the humidity, but usually not enough to bring the humidity up to 100%.
Humidity is important in climate change
Water vapor in the air, the humidity, plays an important part in global climate. Like carbon dioxide, water vapor is a greenhouse gas. Climate scientists have found that carbon dioxide human activities is adding to the air is causing the Earth's average climate to warm. (Related graphic: The greenhouse effect)
This, in turn, is almost surely affecting other aspects of global climate, and could have even bigger effects in the future. (Related: Understanding climate change science)
As the climate warms, the humidity can increase. Since water vapor is a greenhouse gas, it should increase warming as it increases. Measuring how much global humidity is increasing and figuring out how it will increase, and the effects of such an increase are major challenges for climate scientists. (Related: NASA report on warming and humidity)
Answers to questions about humidity
If you have questions about humidity, there's a pretty good chance you'll find the answers in our answers to previous questions, or in our FAQ on humidity.
Absolute humidity: The mass of water vapor in a given volume of air( i.e., density of water vapor in a given parcel, usually expressed in grams per cubic meter
Actual vapor pressure: The partial pressure exerted by the water vapor present in a parcel. Water in a gaseous state (i.e. water vapor) exerts a pressure just like the atmospheric air. Vapor pressure is also measured in millibars.
Condensation: The phase change of a gas to a liquid. In the atmosphere, the change of water vapor to liquid water.
Dewpoint: the temperature air would have to be cooled to in order for saturation to occur. The dewpoint temperature assumes there is no change in air pressure or moisture content of the air.
Dry bulb temperature: The actual air temperature. See wet bulb temperature below.
Freezing: The phase change of liquid water into ice.
Evaporation: The phase change ofliquid water into water vapor.
Melting: The phase change of ice into liquid water.
Mixing ratio: The mass of water vapor in a parcel divided by the mass of the dry air in the parcel (not including water vapor)
Relative humidity: The amount of water vapor actually in the air divided by the amount of water vapor the air can hold. Relative humidity is expressed as a percentage and can be computed in a variety of ways. One way is to divide the actual vapor pressure by the saturation vapor pressure and then multiply by 100 to convert to a percent. Click here for text explaining this in more detail.
Saturation of air: The condition under which the amount of water vapor in the air is the maximum possible at the existing temperature and pressure. Condensation or sublimation will begin if the temperature falls or water vapor is added to the air.
Saturation vapor pressure: The maximum partial pressure that water vapor molecules would exert if the air were saturated with vapor at a given temperature. Saturation vapor pressure is directly proportional to the temperature.
Specific humidity: The mass of water vapor in a parcel divided by the total mass of the air in the parcel (including water vapor)
Sublimation: In U.S. meteorology, the phase change of water vapor in the air directly into ice or the chance of ice directly into water vapor. Chemists, and sometimes meteorologists, refer to the vapor to solid phase change as "deposition."
Wet bulb temperature: The lowest temperature that can be obtained by evaporating water into the air at constant pressure. The name comes from the technique of putting a wet cloth over the bulb of a mercury thermometer and then blowing air over the cloth until the water evaporates. Since evaporation takes up heat, the thermometer will cool to a lower temperature than a thermometer with a dry bulb at the same time and place. Wet bulb temperatures can be used along with the dry bulb temperature to calculate dew point or relative humidity
08-23-2004, 05:32 AM #5
You've been sitting on that info for how long Bama? Just waiting for the chance to post it weren't you? hahahahahaha
08-23-2004, 05:38 AM #6Retired Vet
Originally Posted by Juggy'sTwat
- Join Date
- Nov 2001
08-23-2004, 06:27 AM #7Originally Posted by BOUNCER
Hey Bouncer, good to see u back!! How was the trip? Dumb question i know it was great im sure...
Well, welcome to my world bro. I live in South Florida where the humidity is always high. As soon as u walk outside u start dripping with sweat...errrrrr Thats it, im moving to Ireland...
08-23-2004, 06:33 AM #8Originally Posted by Juggy'sTwat
08-23-2004, 08:13 AM #9Originally Posted by BamaSlamma
08-23-2004, 08:21 AM #10
Hey bouncer how about hooking a fellow irish man up with the golden hammer....in the chat room (keep your sick comments to yourself fellas)
08-23-2004, 08:25 AM #11Originally Posted by mass junkie
08-23-2004, 08:39 AM #12
iv got a golden hammer u can use lol
08-23-2004, 09:11 AM #13Retired Vet
- Join Date
- Nov 2001
Mass, I know a girl who can fix you up with a golden shower if thats any good.
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