cold air doesn't hold as much water vapor than warm air. Why??

Question

The real question:
So then why is it when someone goes into the car, the windows fog up. When the heater is on, it gets worse. Turn on the A/C and it clears it right up... How is that??

i get the whole why ir ges foggy.. but who does the A/C un-fog it

Answer 1

higher temperatures result in the molecules of air spead farther apart from each other. Therefore more moisture is absorbed by the molecules in warm air rather than cold air.

The A/C unfogs windows because an air conditioner essentially cools the air, but also removes moisture...at home or in a car.

Answer 2

Windows fog because the glass is cooler than the air you are breathing out. The water vapor will be attracted to the cooler surface when the air it is floating in comes close to the windshield.
The heater by itself would have to be on full heat and the highest blower to eliminate the fogged up windows.
BUT, the air conditioner actually removes moisture from the air so the fog that was on the windshield moves back into the air and is drawn out by the circulating air condition unit.

Cool air cannot hold as much water vapor as warm because the molecules are more tightly held together which leaves less room for water vapor to attach to the cold air molecules.

Answer 3

If you could check the "vacuum" at the top of a bottle of canned tomatoes it is actually filled with moisture. The amount of moisture at any given time depends on the temperature of the bottle. It you heat the bottle to the boiling temperature, the water vapor pressure will increase to atmospheric pressure and the lid will come off (with no vacuum lefy to hold it on!). At room temperature, the water vapor pressure in the bottle is well below atmospheric pressure (good vacuum!) and is equal to the water vapor pressure in the room if also at 100% humidity. The water vapor ignores the air molecules except to exchange heat by collision and reach the same temperature.

When you breathe out moisture in a cold car, the windshield may be at a temperature well below the dew point temperature of your moisture laden exhalations and water vapor will condense on the windshield. The windshield heater will raise the glass temperature above the dew point and cause evaporation. Running the A/C will provide a very cold cooling coil to recirculated air well below the dew point and condense out (and remove) enough moisture that the relative humidity inside the car will drop below 100% and moisture on the windshield can evaporate. You can still cause fog by breathing directly and closely on the windshield by it will evaporate when you stop.

Answer 4

Since cold air is comparatively saturated to warm air.Even a little more quantity of water might help the cold air to attain saturation point at constant temperature.Warm air can hold more moisture since it has more space(increase in temperature causes increase in volume).That is Charles' Law.There is water vapour present in the atmosphere at all the time.When it comes in contact with the cold surface of the car window it condenses due to decrease in temperature ,this is why the window becomes foggy(settled water droplets).

Answer 5

when cold air and warm combines it become water, now the car is cold and the outside is warn, this causesthe fog, now if that cold air is heated up fast coz of a heater, the water comes out veryfast then if you turn on the ac the warm water in the car has dried up and nothing left, lol this is what i know and learnt

Answer 6

specific its rapidly on the subject of air rigidity bigger the temp the extra water vapour could be suspended interior the air. If temp drops like interior the tropics with hi relative humidity and after sundown then each and every thing will become coated with water.

Answer 7

Hot air is more moist becuase hot air always going up.In to clouds. like firemen say stop drop roll crawl .Cold air more dry because freezes stuff like ice frozen water is not.