The air is thinner, there is less oxygen molecules per volume of air (the air is less dense) therefore to absorb the same amount of O2 into your blood at 4000ft as at 0ft altitude you have to breath more/ more deeply.
Also, you're climbing a mountain (going uphill) which uses more energy than going flat as you have to work against gravity.
there is less air pressure and the air is thinner so you need to breath in more of it then normal
When you climb a mountain it gets harder to breath because the higher you get the less amount of oxygen there is and the more pressure. Your lungs are not used to that so it gets harder to breath.
One more mountain to climb
people experience shortness of breath at top of mountain because of lower oxygen
Soldiers could climb into an enemy's castle more easily.
The mountain itself is not any easier to climb but the clothing and equipment today is smaller, lighter and better built, making the climb more sucessful.
You may have asthma. Have your MD check.
Air becomes less dense as you climb a mountain. This is because at higher altitudes, there is less atmospheric pressure pushing down on the air molecules, causing them to spread out more, making the air less dense.
The original Mother Abbess was Patricia Neway.
The force that makes it difficult to climb a steep mountain is gravity. Gravity is pulling you down towards the ground, making it harder to overcome the incline and requiring more effort to ascend the steep slope.
You run out of breathe easily because the air is more thin
When climbing a mountain, the air density decreases due to the lower pressure at higher altitudes. This decrease in air density can affect breathing and energy levels, making it more challenging to climb as you reach higher elevations.