What’s the ratio of air to water at that percent? Is there a cap on the amount of moisture in the air? Is it the same for different elevations?
In: Earth Science
If you live in Florida like I do – it means you are going to be sweating in places that you don’t want to sweat in.
The air becomes solid water!
But seriously, it is just the max amount of water that the air can “absorb”. It is a relative number, and the physical amount will vary based on air temperature. So 10% humidity in cold air is not the same amount as 10% in hot air.
Basically if 100% humidity happens, than it is likely to rain. Keeping in mind that humidity also varies based on altitude as well, so if it is X amount humid at the surface, it means up high where it is colder, the % humidity is likely to be more, causing high potential for rain.
“What’s the ratio of air to water at that percent?”
It depends on the temperature. There’s more water at 80 degrees and 100% relative humidity than at 60 degrees and 100% rh.
At 100% rh and 60 degrees there’s 0.0107 pounds of water for every pound of air. At 80 there’s 0.02244 pounds of water per pound of air.
Bonus round: supersaturation (RH>100%) is possible as well, though it is short lived and usually happens in clouds..at best you briefly add a percent or two on top of the 100.
>What’s the ratio of air to water at that percent?
Sorry not ELI5, but here is the equation that answers this question:
h = 1e-2 * RH * p_vp / p
where:
h = fraction of air molecules that are H2O
RH = relative humidity, expressed as percentage
p_vp = vapor pressure of water (increases with ambient temperature)
p = ambient pressure
> What’s the ratio of air to water at that percent?
That depends on the temperature. At the freezing point of water (0°C), air at 100% humidity has about half a percent of water by weight, while on a hot day (30°C), air at 100% humidity has about 3% water.
It means it feels like hot as hell and you sweat like crazy. It means that when you run you feel like it’s 150 outside. And to those people who state Arizona and places like that are different because of low humidity, let me tell you hot is hot. So don’t let anyone talk you into moving to a place because it’s dry heat. Hot is freaking hot, ok.
When people say the humidity is 50%, they’re really talking about the *relative* humidity. That’s a comparison between how much water vapor is in the air and how much the air can possibly hold at that temperature. The actual amount of water the air can hold varies with temperature and pressure, but generally hot air can hold a lot more than cold air.
When the number gets to 100%, that means the air can’t take any more water. At that point, your sweat doesn’t really evaporate, so you tend to be covered in sweat as your body tries to cool itself. Anything colder than the air, like a soda can, will be covered in water, because the air next to it gets cooled down, can’t hold the water it already has in it, and dumps that water onto the can.
You’ll also see water dripping out of air conditioners, because they use cold coils to cool the air, and that also makes water come out of the air. That’s also why your sweat dries up so fast when you walk into an air conditioned building.
The air can hold a certain amount of water. That amount changes based on the air temperature. The percent humidity is the percent of water the air has already absorbed compared to what it can totally absorb. That percent can change as the temperature changes, even if the amount of water in the air stays the same.
It means the air is fully saturated with water. This is very similar to when you have a glass of tea and you’re dissolving sugar in it, there is a point where if you add any more sugar, the sugar will just sit on the bottom and not dissolve into the tea. This is the saturation point and it occurs when water vapor is dissolving in air as well. once the air reaches 100% humidity, it has reached it saturation point.
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