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When we are in a room, especially in some old houses, we feel this sudden rush of cold air. How does a strong air current arise and pass away so quickly?(lasts for about a second) I know air-currents are caused by pressure differences. But can pressure difference of the magnitude required to generate an air current be created within a second? If so , please answer with equation that relates the pressure and Temperature with time interval. Thanks..i hope I am now much clearer with my question. (I am inclined to think in the direction of something similar to a weather situation)

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    $\begingroup$ Nothing happens without a reason - especially not in physics. Please provide a link to some YouTube video where "we" can observe what you mean. $\endgroup$
    – Metalbeard
    Commented Jul 9, 2013 at 9:48
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    $\begingroup$ If I had the reason why it happens I would not have asked the question. $\endgroup$
    – Nix
    Commented Jul 9, 2013 at 9:50
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    $\begingroup$ @Nix How is it possible that you entered a closed house without opening a door? $\endgroup$
    – anna v
    Commented Jul 9, 2013 at 10:35
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    $\begingroup$ I am thinking of chimneys. In a closed house the air will have equalized , and a sort of warmer "bubble" could be trapped at the top of the chimney. With the opening and closing of the door a small slow impetus, starts again the updraft in the chimney, and it stops because the doors are closed. This "bubble" could be semi stable for a while against the updraft but when it moves, air from the colder basement comes up. Chimneys have been used in the middle east since ancient times to cool houses and buildings. The taller the chimney the stronger the updraft. $\endgroup$
    – anna v
    Commented Jul 9, 2013 at 10:43
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    $\begingroup$ environmentalgraffiti.com/green-living/… $\endgroup$
    – anna v
    Commented Jul 9, 2013 at 10:47

2 Answers 2

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I will try to use the solar chimney effect in explaining sudden drafts in a closed house. It is a guess, and certainly not worth the trouble of writing equations.

In its simplest form, the solar chimney consists of a black-painted chimney. During the day solar energy heats the chimney and the air within it, creating an updraft of air in the chimney. The suction created at the chimney's base can be used to ventilate and cool the building below.1 In most parts of the world it is easier to harness wind power for such ventilation as with a windcatcher, but on hot windless days a Solar chimney can provide ventilation where otherwise there would be none.

First of all in a very cold environment one would not notice more chill in a closed house. Chimneys are usually well exposed to the sun, the air inside getting heated faster than outside so there is an updraft forming. A completely closed house with a chimney will reach an equilibrium point, where the under pressure in the house generated by the updraft balances the force of the updraft.

If a door is opened and shut, an impulse travels through the house as the air tries to equillibrate with the outside pressure. This will reach the chimney and release the updraft. It will take some time to reach the chimney if it is in another room or another floor. Once it reaches the chimney a pulsed updraft starts, sucking air from the house and the basement which is cooler will be the supplier of this air. The duration of the pulse should be the time of opening and shutting the door.

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  • $\begingroup$ That explains why I have observed/felt this in old houses. They all have chimneys. Thank you :) $\endgroup$
    – Nix
    Commented Jul 10, 2013 at 6:45
  • $\begingroup$ Solving the convective equations are turning out to be tough- there are just too many parameters. $\endgroup$
    – Nix
    Commented Jul 10, 2013 at 6:46
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After our discussion I summarise your question: Is it possible that a sudden rush of cold air blows for about one second in a closed room?

The answer must be: No. Theoretically, you could create huge temperature gradients by heating/cooling the walls to create such movement. But this has nothing to do with reality.

We are stuck with some door/window opening and closing that could cause air to move. Or something else moves within the room, stirring the air. In this case, wind chill could even make the air feel colder, but this has nothing to do with a meteorological situation outside.

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  • $\begingroup$ thanks...for the meteorological part. that takes care of it then. :) So stirring of air has to happen- i guess that's what you mean. $\endgroup$
    – Nix
    Commented Jul 9, 2013 at 10:40
  • $\begingroup$ So the room is not closed. Thank you anna v for the link. $\endgroup$
    – Metalbeard
    Commented Jul 9, 2013 at 11:01

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