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Why does unsaturated air become saturated when cooled or without cooling?

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The vapor pressure of water is directly proportional to temperature. So a certain amount of water vapor (for instance, 1 mg per cubic meter) at a high temperature is well below the total amount that that volume can contain, but if you cool that same volume to a low temperature it's the total amount that the volume can contain. In other words, a particular amount of water vapor is 100% of what that volume of air can "hold" at 10 degrees, but only 50% of what the air can hold at 90 degrees. (I just made the temps up, they're not accurate.)

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can you make it into simpler terms
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I'll try. Saturated means that the amount of water vapor is at 100% of what the air can hold at that temperature. Cold air holds less water than warm air. Sit a cold glass of water on the table in summer and moisture condenses on the outside, right? That's because the air touching the glass has been cooled to the point that it can no longer keep all the water vapor in gas form. At the surface of the glass the air is 100% saturated, in fact it's more than 100% since the water is actually coming out of its vapor form and turning to liquid. No water was added to the air, all that happened was that the water already there could not be retained in vapor form at the cold temperature.
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Thanks very helpful.
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Thanks
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Saturation decreases as the temperature decreases.

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He knows that; the question is "why"?
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Oops, read your answer wrong. Your answer is wrong. Saturation increases as temperature decreases.
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No, if you put sugar in cold water and hot water, they both dissolve. Keep adding sugar, the hot water can hold more sugar than the cold. The cold water will have sugar on the bottom, therefore being saturated, while the hot water can still carry more.
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Wait, nope. My bad, wrong concept! You're right!
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