Tropical circulation basics: Which statements correctly describe heating and large-scale air motion in the tropics?

Introduction:
Earth’s general circulation is powered by differential heating: strong insolation in the tropics versus weak in the polar regions. This question checks fundamental concepts behind Hadley circulation and meridional heat transport.

Given Data / Assumptions:

• Greater solar input at low latitudes.
• Air expands and becomes buoyant when heated.
• Upper-level return flow connects low and high latitudes.

Concept / Approach:
In the tropics, intense surface heating causes air to warm, expand, and rise near the Intertropical Convergence Zone (ITCZ). Aloft, mass continuity drives outflow poleward; near the surface, relatively cooler, denser air moves equatorward to replace rising air, closing the cell as trade winds after Coriolis deflection.

Step-by-Step Solution:
Recognize higher net radiation in tropics versus polar regions → stronger surface heating.Warm air becomes less dense and rises; surface pressure falls, drawing in cooler air from higher latitudes.Upper tropospheric outflow carries momentum and heat poleward as part of the Hadley cell.All statements are consistent with the Hadley circulation framework → choose combined option.

Verification / Alternative check:
Reanalysis datasets show rising motion in the deep tropics, poleward outflow near 200–300 hPa, and surface return trades—consistent with textbook circulation models.

Why Other Options Are Wrong:
Any single statement alone is incomplete; the general circulation requires all three components.None of the above is contradicted by basic climatology.

Common Pitfalls:
Ignoring Coriolis deflection (which shapes trades) or confusing seasonal monsoon variability with the mean annual circulation.

Final Answer:
All of the above.