# Why is atmospheric pressure the same indoors?

• mcmath
In summary, the typical explanation for atmospheric pressure is that there is a column of air sitting on us, creating a pressure of 101 kPa. However, even if there is a ceiling above us, the atmospheric pressure remains the same due to the density gradient of air and the ability of air to seep through tiny cracks and exert pressure from all sides. This is why even when indoors, the top of our head still feels the same 101 kPa pressure.

#### mcmath

Hi, apologies in advance as I feel stupid for asking this, but believe me I tried googling. The typical explanation for atmospheric pressure is that there is a column of air sitting on us, creating a pressure of 101 kPa. But what if there's a ceiling above us? Now only a few feet of molecules is directly above our heads. Why doesn't atmospheric pressure change? I remember vaguely from a physics course that it's related to pressure being a state function only dependent on elevation, and that pressure is applied in all directions at the given elevation. So I can understand that my arms may feel the 101 kpa pressure, but if I'm indoors, why does the top of my head still feel the same 101 kpa pressure?

Welcome to PF!
mcmath said:
The typical explanation for atmospheric pressure is that there is a column of air sitting on us, creating a pressure of 101 kPa. But what if there's a ceiling above us? Now only a few feet of molecules is directly above our heads. Why doesn't atmospheric pressure change?
Imagine you pumped all the air out of your house. Is your house air tight? What keeps the air from pouring off the roof of your house and in through the cracks between your front door and its frame?

ok, so I guess a better explanation of atmospheric pressure is that there is a density gradient of air, with the density being heaviest at ground level?

I guess my main point of confusion is when people explain atmospheric pressure to me as a column of air above our heads, extending miles into the air, which would mean the 101kPa pressure is from the billions of air molecules pressing down on my head, which makes sense only if you're outdoors

mcmath said:
I guess my main point of confusion is when people explain atmospheric pressure to me as a column of air above our heads, extending miles into the air, which would mean the 101kPa pressure is from the billions of air molecules pressing down on my head, which makes sense only if you're outdoors

Well, this column likes to seep through any tiny crack and push in from all sides.

## 1. Why is atmospheric pressure the same indoors?

The reason why atmospheric pressure is the same indoors is because the air inside a building or room is still part of the Earth's atmosphere. Atmospheric pressure is the weight of the air above us, and this weight is evenly distributed throughout the atmosphere, both indoors and outdoors.

## 2. Does the height of a building affect indoor atmospheric pressure?

No, the height of a building does not affect indoor atmospheric pressure. The weight of the air above a building is balanced by the air pressure pushing up from below, so the overall atmospheric pressure inside the building remains the same as at ground level.

## 3. Can indoor atmospheric pressure change?

Yes, indoor atmospheric pressure can change due to factors such as temperature, humidity, and ventilation. For example, if a room is heated, the air molecules will become more energetic and spread out, resulting in a decrease in atmospheric pressure. Similarly, if a room is poorly ventilated, the buildup of carbon dioxide can also lead to a decrease in atmospheric pressure.

## 4. How does atmospheric pressure affect humans indoors?

Atmospheric pressure plays an important role in the functioning of our respiratory and circulatory systems. The level of atmospheric pressure affects the amount of oxygen that is available for our bodies to use. In areas with high altitude and therefore low atmospheric pressure, people may experience difficulty breathing due to the lower amount of oxygen in the air.

## 5. Can indoor atmospheric pressure affect weather patterns?

Indoor atmospheric pressure does not have a direct impact on weather patterns. However, changes in indoor atmospheric pressure can be an indicator of approaching weather changes. For example, a sudden decrease in indoor atmospheric pressure may signal the arrival of a storm or low-pressure system.