What is the effect of altitude on gas pressure?

As altitude increases, gas pressure decreases due to the thinning of the atmosphere.

In more detail, gas pressure is a measure of the force that gas molecules exert on a given area. At sea level, the weight of the atmosphere above us exerts a certain pressure, which we refer to as atmospheric pressure. This pressure is due to the weight of the air molecules above us, pushing down on us.

As we ascend in altitude, the number of air molecules above us decreases. This is because the atmosphere gets thinner the higher you go. As a result, the weight of the air above us decreases, and so does the pressure it exerts. This is why gas pressure decreases with increasing altitude.

To understand this better, imagine a column of air stretching from the ground up to the top of the atmosphere. At the bottom of this column, at sea level, the pressure is highest because the weight of all the air in the column is pushing down. As you climb up the column, there is less air above you, so the weight pushing down is less, and the pressure decreases.

This effect is noticeable even over relatively small changes in altitude. For example, if you've ever climbed a mountain or flown in an aeroplane, you may have noticed that your ears 'pop'. This is because the change in pressure affects the air inside your ears.

In summary, the effect of altitude on gas pressure is a decrease in pressure as altitude increases. This is due to the reduction in the weight of the air above us as we ascend, resulting in less force being exerted on a given area.