The Reason for the Seasons

EARTH’S TILTLength of Day – Angle of Rays

Why do we have seasons? Are the Seasons caused by the Earth being closer to or farther

away from the sun?

NOCloser to the sun in January, and farther away in July.

Perihelion is the point along Earth’s orbit when Earth is closest to the Sun.

January

Aphelion is the point along Earth’s orbit when Earth is farthest from the Sun.

July Distance A

Distance B

Distance B (the tilt) is so small that it really does not make us any closer to the sun.

Why do we have seasons?Seasons are caused by different amounts of sunlight reaching earth because of a combination of

1. The tilt of Earth and2. It’s revolution around the sun

Sun’s Path Across Sky

Sun’s Path Across Sky

Flashlight Activity

Flashlight Activity

NO – The amount of energy leaving the flashlight is the same at all times.

Likewise, the average amount of energy leaving the Earth receives is the same.

The energy is more concentrated in “A” because the energy is in a smaller area, therefor the temperature would be warmer. In B, the energy is spread out over a larger surface, decreasing the concentration and temperature.

In summer, the light hits us more direct, like in part “A”, the concentration is greater, we get a lot of heat therefore temperatures are warmer on average.

In winter, the light hits us indirectly, like in part “B”, the light is less concentrated and spread out, we get a little bit of heat therefore temperatures are cooler on average.