The Reason for the Seasons

The earth’s changing seasons are NOT due to distance from sun

January July

Earth’s orbit is almost a perfect circle

• Earth is CLOSEST to our Sun (91 million miles) in winter—January 3

• Earth is farthest from on our Sun (94 million miles) in summer –July 4

The seasons change due to two factors:

1. The earth’s axis is tilted 23.5 so the northern ⁰hemisphere tilts toward and away from the sun

AND…..

2. Direct rays of the sun carry more energy per unit of area

When its hot in the summertime, the sun’s rays hit the surface more directly

(energy is concentrated.)

When its cold in the winter, the sun’s rays hit the surface at a lower angle—same energy is more spread

out.

The angle of the sun above the horizon changes because…..

• We are tilted more towards the sun (more overhead) or away from the sun (at lower angle.)

The length of the days changes because…..

When tilted toward the sun, we actually spend more time in the suns light.