Why do ears pop at high altitudes?

Ears pop at high altitudes due to changes in air pressure affecting the eardrum and the Eustachian tubes.

When you ascend to high altitudes, the air pressure decreases. This change in pressure can cause discomfort in your ears. The reason for this is that your middle ear and the outside world are connected by a small tube known as the Eustachian tube. This tube helps to equalise the pressure between the middle ear and the outside environment.

As you ascend, the air pressure outside your ear decreases more rapidly than the pressure in your middle ear. This creates a pressure difference, causing your eardrum to bulge outwards. This is what causes the discomfort or 'fullness' you might feel in your ears.

To alleviate this pressure difference, your body will try to equalise the pressure. It does this by opening the Eustachian tubes to allow air to flow from the middle ear to the back of the nose and throat, where the pressure is lower. When this happens, you might hear a 'pop' sound. This is the sound of the Eustachian tubes opening and air rushing out to equalise the pressure.

The same process happens in reverse when you descend from high altitudes. The air pressure outside your ear increases more rapidly than the pressure in your middle ear, causing your eardrum to bulge inwards. Again, your body will try to equalise the pressure by opening the Eustachian tubes to allow air to flow into the middle ear. This can also cause a 'pop' sound.

In summary, the 'popping' of ears at high altitudes is a natural response of your body trying to equalise the pressure in your middle ear with the outside environment. It's a fascinating example of how our bodies adapt to changes in our surroundings.