Position of Earth affecting the climate

Strength of the sun

Only about 40 per cent of the solar energy intercepted at the top of the atmosphere passes through to the Earth’s surface.

Almost all of the energy that affects the climate on the Earth originates from the Sun.

The energy emitted by the sun passes through space until it hits the Earth’s atmosphere.

Only about 40 per cent of the solar energy intercepted at the top of the atmosphere passes through to the Earth’s surface.

The rest is reflected or absorbed by the atmosphere. The energy output of the sun is not constant, it varies over time and it has an impact on our climate.

Changes in the Earth’s orbit

The Earth’s orbit around the Sun is an ellipse, not a circle but the ellipse changes shape.

Sometimes it is almost circular and the Earth stays approximately the same distance from the Sun as it progresses around its orbit.

At other times the ellipse is more pronounced so that the Earth moves closer and further away from the sun as it orbits.

When the Earth is closer to the sun our climate is warmer.

Circular orbit.

Elliptical orbit – when the Earth is closer to the Sun, its climate is warmer.

Changes in the orientation of the Earth’s axis of rotation

The Earth showing angle of axis of rotation. When the angle increases the summers become warmer and the winters become colder.

The Earth rotates around an axis (imagine a line that joins the north and south poles) but the Earth’s axis is not upright, it leans at an angle.

This angle changes with time and over about 41 000 years it moves from 22.1 degrees to 24.5 degrees and back again.

When the angle increases the summers become warmer and the winters become colder.