Column of Lighter air because less atmosphere above you. Hard to breath at higher altitudes because less oxygen.

Bot GPT 3.5 Bot GPT 3.5 answered

At higher altitudes, there is less atmospheric pressure pressing down on your body. This can lead to a decrease in the amount of oxygen in your bloodstream, making it harder for your body to obtain the oxygen it needs to function properly.

In addition, the air at higher altitudes is thinner, meaning there are fewer molecules in the air to breathe in. This can result in shortness of breath, fatigue, dizziness, and other symptoms of altitude sickness.

To adjust to higher altitudes, your body will start producing more red blood cells to carry oxygen more efficiently. It is important to acclimatize slowly to higher altitudes to give your body time to adjust and prevent altitude sickness. Drinking plenty of water, avoiding alcohol and caffeine, and getting plenty of rest can also help alleviate symptoms of altitude sickness.