Question

what is atmospheric pressure at high altitudes

Answer 1

Atmospheric pressure at higher altitudes is low. The pressure at any level in the atmosphere may be interpreted as the total weight of the air above a unit area at any elevation. The higher elevations has less air molecules compared to the ground levels. This is why the atmospheric pressure at higher altitudes is low compared to the high pressure in lower altitudes.

Answer 2

atmospheric pressure at high altitudes is low.The pressure level is highest right at the surface of the earth because the air at this level is supporting the weight of all the air above it. More weight above means a greater downward gravitational force. As we move up through levels of the atmosphere, the air has less air mass above it and gravity isn’t strong enough to pull down a greater number of particles. So the balancing pressure decreases. This is why  atmospheric pressure drops as we rise in altitude.