The Earth is quite large, but the layer of dense air around it is not very thick, reaching a height of about 11 kms, where 3/4 of the planet's air mass is located. Compared to the radius of the Earth (approx. 6371 kms), the denser air layer is only about 0.17%. For example, on a globe with a diameter of 30 cm, only a layer of about 1/4 mm would correspond to this, which is comparable to the thickness of a thin layer of dust or a sheet of paper.