why people gasp when climbing a tall mountain?

Answer 1

The higher in altitude you go, the less dense the air becomes. Climbing a tall mountain adds two factors that cause a person to gasp. One is the fact that since you are trying to breathe the same volume of air, it takes deeper breaths or more rapid breaths to compensate for the lower density. Also, because climbing uphill is strenuous, you need more oxygen than if you were resting.

Answer 2

Its as simple as why one gasps while running. The more physical work you do, the more oxygen is utilized from your lungs for energy generation thus requiring deep inhalations to get the necessary oxygen from outside. This is the primary reason. The secondary reason is related to the air density thingy that others are talking about.

Thanks

Answer 3

Because the oxygen content in the air decrease when the altitude (height from the earth ) increases.

Answer 4

Because there is less oxygen at higher altitudes, so as you get higher on the mountain, you have to breathe harder to get all the oxygen your body is used to getting.

Answer 5

As altitude increases, air thins.
Also, exertion.