Why Earth’s Tilt Creates the Seasons
(remember, the Sun is SO large and SO far away, that the beams that get to Earth are parallel)
Northern Hemisphere Summer:
The North hemisphere axis is
tilted towards the Sun the most
around June 21st.
Northern Hemisphere Winter:
The North hemisphere axis is
tilted away from the Sun the
most around December 21st.
NP
NP
Light
Light
Equator
SUN
Equator
Night
time
SP
SP
In summer there is a larger angle of separation
(angle between horizon-blue line and Sunorange line) than winter, so there’s more direct
light. Plus, beams of light cover less surface
area, so the light is more intense. More heat
energy is absorbed, so the weather is warmer.
In winter there is a smaller angle of separation
(angle between horizon-blue line and Sunorange line) than in summer, so there’s less
direct light. Plus, beams of light cover more
surface area, so the light is less intense. Less
heat energy is absorbed, therefore the weather is
cooler.
The atmosphere (dotted circle around Earth) also affects how much heat energy Earth receives
at a particular location.
1. When the north is tilted toward the Sun, there is less atmosphere to go through so more heat
energy hits Earth’s surface.
2. When tilted away, there is more atmosphere to go through, due to Earth’s curvature, so heat
energy is reflected off the atmosphere more. What does go through is scattered more so less
hits Earth’s surface.
Night
time