On a round Earth, the same sunbeam is squeezed onto a small patch at the equator but smeared across a wide area at the poles — so the tropics roast and the poles freeze.
- The Earth is spherical , so the Sun’s rays strike different latitudes at different angles.
- Rays on the equator are concentrated over a smaller area (warm), while at the poles the same energy spreads over a larger area (cold).
- The spherical shape and axial tilt also cause seasons and changing day length, so solar radiation is unevenly distributed — driving global winds and ocean currents.