Assertion (A) : The thickness of the atmosphere is maximum over the Equator. Reason (R) : High insolation and strong convection currents occur over the Equator.

Both Assertion and Reason are true, and Reason correctly explains the Assertion. Observations show the troposphere is ~18 km high at the equator and only about 8 km at the poles; thus tropospheric thickness is maximum over the equator [1]. This larger thickness is attributable to intense solar heating in the tropical belt which warms the column, producing strong convectional updrafts that transport heat and moist air to much greater heights; textbooks explicitly note heat is carried to great heights by strong convectional currents at the equator, raising the tropopause altitude [2]. The Inter-Tropical Convergence Zone (ITCZ) exemplifies this process: maximal insolation drives convergence and deep convection, lifting the tropospheric top over the equator [3].

Sources

1. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 20: Earths Atmosphere > Troposphere (0 to 12 km) > p. 274
2. [2] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 7: Composition and Structure of Atmosphere > STRUCTURE OF THE ATMOSPHERE > p. 65
3. [3] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 9: Atmospheric Circulation and Weather Systems > General circulation of the atmosphere > p. 80