The troposphere is the lowest layer of the Earth's atmosphere, extending from the surface up to an average height of about 8-15 kilometers (5-9 miles). It is where weather phenomena occur and where the majority of Earth's air mass is located. The thickness of the troposphere is not constant around the planet and varies depending on several factors.

The troposphere is thickest at the Equator. This can be attributed to a combination of factors, including the distribution of solar energy, temperature variations, and atmospheric circulation patterns.

Distribution of Solar Energy:
- The Equator receives the most direct sunlight throughout the year, resulting in higher temperatures in this region.
- The solar energy absorbed by the Earth's surface at the Equator leads to strong convective activity, causing warm air to rise and creating a vertical circulation pattern known as the Hadley cell.

Temperature Variations:
- Temperature decreases with increasing altitude in the troposphere. However, the rate at which temperature decreases, known as the lapse rate, is not constant.
- At the Equator, the average temperature is higher compared to the poles. This means that the temperature gradient in the lower troposphere is larger at the Equator.
- The larger temperature gradient at the Equator leads to a greater temperature difference between the surface and the upper troposphere, resulting in a thicker troposphere in this region.

Atmospheric Circulation Patterns:
- The Hadley cell is a large-scale atmospheric circulation pattern that dominates the tropics and subtropics.
- In the Hadley cell, air rises at the Equator due to strong convective activity, moves poleward at higher altitudes, and descends in the subtropical regions.
- The descending branch of the Hadley cell creates a subsidence inversion, which acts as a lid and limits the vertical extent of the troposphere in the subtropics.
- This subsidence inversion results in a thinner troposphere in the subtropical regions compared to the Equator.

In summary, the thickness of the troposphere varies around the planet, with the troposphere being thickest at the Equator. This is due to a combination of factors, including the distribution of solar energy, temperature variations, and atmospheric circulation patterns. The greater solar energy received at the Equator, larger temperature gradient, and the presence of the Hadley cell contribute to the thicker troposphere in this region.