|MadSci Network: Earth Sciences|
As you may know, the tilt of the earth's spin axis is the reason for the seasons. In the summer, the northern hemisphere points more towards the sun, so the sun rises earlier, is higher in the sky at noon, and sets later. Because of this extra sunlight, the ground and air get warmer, and we call it summer.
Of course, the southern hemisphere is pointed away from the sun when it is summer, so they get cold. In the south, December 21 is the first day of SUMMER, and June 21 is the first day of WINTER. (Remember that if you ever visit Australia!)
Anyway, if there were no tilt to the earth's axis, the sun would rise and set at the same time every day, and the weather would never change. It would be "spring-like" year-round. However, most living things have adapted to the seasonal variations, and might be very unhappy without seasons, so I am not sure we should wish them away.
By the way, some people think that we get hotter in summer because we are closer to the sun. That's absolutely wrong! The earth-sun distance changes by only +/- 1.5 percent of its average value, which is not enough to make much difference. You can tell that, because we are closest to the sun on (about) January 2 each year, and it sure is cold!
I hope that helps!
- Doug Finkbeiner (friend of Erin Cram)
Try the links in the MadSci Library for more information on Earth Sciences.