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Everyone have probably seen the phenomenon as one opens a cold ice cream from its pack, a white cloud begins to flow around the ice cream surface, and it constantly spreads out until the ice cream warms.

How can this effect be described? Where does the cloud come from and how it forms? Is there anything special about ice creams or the same would happen to a cold steel object for example? (I couldn't actually see any cloud around a cold glass but still have to work on it). What more experiments/observations could be useful to study this effect?

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If I'm not mistaken, a similar effect happens near all sufficiently cold bodies: moisture from the air condenses and becomes visible when cooled from room temperature, a process similar to cloud formation. The reason it stops forming after some time, near ice cream or otherwise, is because the object gradually warms up to room temperature. If the foggy layer is still enough (e.g. we have liquid nitrogen in a thermally isolated jar and between the nitrogen and air there is a layer of condensed moisture), it actually serves as an insulator and somewhat prevents the sublimation/vapourising of the cold object.

In labs which use liquid nitrogen or helium for cooling, an even more awesome thing happens, which is somewhat of a level up to the ice cream fog: the moisture not only condenses, but solidifies and forms ice on the metallic sections of tubes and containers.

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    $\begingroup$ It also happens on space rockets, where a tank of liquid oxygen covers itself with ice and thus adds insulation to itself. $\endgroup$ – Martin Kochanski Jun 5 at 7:02
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Mist is tiny droplets of water hanging in the air. These droplets form when warmer water in the air is rapidly cooled, causing it to change from invisible gas to tiny visible water droplets. Mist often forms when warmer air over water suddenly encounters the cooler surface of land. -National Geographic Society

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It is because of condensation of water vapour available in the air. BUT why there is not a cloud every time one has an icecream? that comes down to the dew point and wet temperature of the air in that room/place (aka ambient). Basically the amount of water vapour in the ambient air + the temperature of the ambient air dictates the presence or absence of the cloud.

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Water vapour from the air condensed and appear as white clouds. These white clouds diappear after some time because they gained heat and evaporated.

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