We all know that in the winter the days are shorter than the summer, but is that really the reason for the seasons? Actually, not really. If that were the case, places in Alaska where the sun is up 24 hours for the day would be hotter in the summer than at the equator where the day length is closer to 12 hours.
The real reason for the season has to do with how high the sun sets in the sky. When the sun is directly overhead it’s energy is more intense to a spot on the globe. Take a look at the chart below. When the sun only reaches 26° above the horizon, it’s less than half as effective when the sun is overhead.
There are some great websites to study the position of the sun and the changes of day length through the year. The first is the World Clock from timeanddate.com. This will show you where the sun is directly overhead along with the position of the moon and there there is sunlight and where this is night or dusk.
Another great sight is Gaisma.com. This sight will show the path of the sun for the current date, at the equinoxes and the solstices. Here is a sample for Altoona.
What you will find through looking at all of these sites is that the sun changes it’s position and day length changes the most in the month on either side of the equinoxes with little change around the times of the solstices.