(a) Heated air expands, becomes lighter, and is pushed upward by cooler and heavier currents of air.
(b) Air currents travelling towards a region of more rapid motion have a tendency to "lag behind," and so appear to travel in a direction opposite to that of the earth's rotation.
2. Data:
(a) The most heated portion of the earth is the tropical region.
(b) The rapidity of the earth's motion is greatest at the equator and least at the poles.
(c) The earth rotates on its axis from west to east.
3. Inferences:
(a) The heated air in equatorial regions will be constantly rising.
(b) It will be pushed upward by colder and heavier currents of air from the north and south.
(c) If the earth did not rotate, there would be constant winds towards the south, north of the equator; and towards the north, south of the equator.