When Troposphere Is Thick?

The troposphere is between 5 and 9 miles (8 and 14 kilometers) thick depending on where you are on Earth. It's thinnest at the North and South Pole.

What causes the thickness of the troposphere?

The Reason: Temperature

Therefore, the same amount of air molecules over the equator must extend further upward than the air molecules in the coldest regions on Earth, the poles. Thus, the atmosphere is thickest and deepest at the equator, as the air molecules take up far more space there than anywhere else.

During which season is the troposphere the thickest?

The height of the top of the troposphere varies with latitude (it is lowest over the poles and highest at the equator) and by season (it is lower in winter and higher in summer).