What causes uneven heating of earths surfaces?

Answer 1

This is caused by the earth's tilt. Vertical rays of the sun hit the earth at points between 23.5 degrees of the equator. Where ever the radiation is perpendicular to the surface, radiation is being maximized, and therefore must be transported elsewhere around the earth to account for this uneven heating.

1) the amount of sunlight falling on the surface per unit area (say square foot):

thus time of day, angular displacement from vertical for the sun (how close to the poles vs the equator AND the season).

2) the amount of light energy that get absorbed vs reflected back up.

(e.g., snow reflects almost all the light, sea water (dark) absorbs most)

3) the specific heat of the substance that the light is striking.

(it's hard to heat up water, easy to heat stone)

4) Cloud cover.

Answer 2

Sunlight hits the equator at a more direct angle than it hits the poles, adding more energy to the air near the equator and thus heating it more.