Atmospheric Pressure: Why Does It Stay the Same?

[prasanna]

I always wondered

When you are standing on an open area. the pressure exerted by atmosphere on your head is the total weight of the atmosphere column just above your head.Of course, divided by the area of your head.

When you are inside a closed room!
Even then the atmospheric pressure does not change! In spite of the air column above your head being on about 4-5 ft.!
Why?

 

[Tjl]

Because pressure, like liquids, tends to move towards regions of less pressure. In your case, the air would move into the house, to increase the pressure.

Also try to view pressure as the impact between particles not as a solid weight. So pressure then would be dependent on the volume, density, and KE of the air. If you care to learn more, try researching Browning motion.

 

[Diane_]

Building on what the response above says: fluids transmit pressure equally in all directions. Assuming the house isn't air-tight, the pressure outside the house will be the same as that inside the house. You can see this in part by using something called Pascal's Vessels. Look here:

http://nimrod.phy.uc.edu/demoweb/fluids/fdemo/pascal.htm

As you can see, they're basically weird-shaped tubes connected at the bottom. Regardless of the shape of each tube, when you fill them with water, the water level rises to the same height in each of them. The pressure in each is the same.

You can view it, if you will, as indicated in the post above. If the pressure in the house were to drop, there would be a tendency for air to flow into it until the pressure was equalized. If the pressure were to increase, the reverse would happen. Have you ever noticed that, when you walk into a house where air conditioning is operating, there's a slight to strong wind blowing through the door? Guess where that comes from. :)