SEASONS

 

First and foremost….It is not warmer in the summer because we are closer to the Sun.  Lots of people believe this, but it is just not true. In fact, when it is summer in Lenox, the Earth is actually at its farthest point from the Sun.

 

So what causes the seasons???

 

2 things

 

              The earth is tilted at 23.5 ˚

              The axis always points to Polaris           

              Polaris is known as the North Star

 

 

The arrows to the right represent light rays from the sun.  Because the Sun is so big compared to the Earth, only the rays that come straight at Earth will hit it.  The light rays that are hitting the earth at 90 degrees are known as direct rays.  Here they hit the earth in the red area. Because the Earth is curved, not all rays hit it directly.  Light rays that hit the earth at an angle are known as indirect rays (green area).  Areas of the Earth that are hit by direct rays are warmer than areas that are hit by indirect rays.  The equator (yellow) is always hit by direct rays of the sun.  This is why it is always warm there.  The poles are always being hit by indirect rays.  That is why it is cold there. 

 

 

 

 

Take a look at the picture above.  It shows the earth in different positions in its orbit.  Polaris would be way off to the left.  The Earth can be divided into 2 halves, a North hemisphere and a South hemisphere.  Since the tilt of the Earth is always  pointed in the same direction (toward Polaris), different hemispheres get more or less direct rays at different times of the year.  Look where it says “summer” above.  The direct rays of the sun are hitting the Northern hemisphere.  Except at the equator, the Southern hemisphere will only get indirect rays.  This is why we have summer in June; the earth is in this position in its orbit.  In Australia, which is in the Southern hemisphere, only indirect light is present, so they experience winter in June.  On the opposite side of the orbit, where the diagram says “winter”, the Northern hemisphere is tilted away from the sun.  The Southern hemisphere is tilted toward the sun.  This time, the South gets more direct rays than the North, so it is winter in the North and summer in the South.

 

During spring and fall, neither hemisphere is tilted more toward the Sun.  Direct rays hit only at the tropical zones near the equator.  Indirect rays hit pretty much everywhere else.  Therefore we have mild temperatures in the north and south away from the equator.