ROCHESTER, NY (WROC) – No matter what season it is, the “sun angle” is referred to quite frequently in terms of how it affects things like our daily temperatures and snow cover. 

The sun angle is defined as the angle at which the sun strikes the Earth. Simple enough right? It’s a fairly straightforward definition, but it’s actually a very influential and complex phenomenon that dictates how much heat energy the Earth receives at a particular time and place that affects everyone differently.     

The reason we have seasons is because of the varying sun angle due to the earth’s 23.5° tilt on its axis. As the earth rotates and orbits around the sun, different parts of the earth get exposed to different amounts of sunlight throughout the year. 

Image courtesy of NWS

During our summer the sun angle is highest when the northern hemisphere is tilted towards the sun. This is when the sun appears highest in the sky, and provides longer days that add more heat energy to the earth’s surface. During our winter the sun angle is lowest as the northern  hemisphere is tilted away from the sun. This is when the sun appears the lowest in the sky, our days are shorter, and therefore our temperatures are colder. 

Image from: http://www.ces.fau.edu/nasa/module-3/why-does-temperature-vary/angle-of-the-sun.php

This variation in sunlight ultimately affects our seasonal temperatures as the angle of the sun striking the earth also varies at different locations and latitudes. As seen in the above photo, the sun’s rays strike the earth at the equator where the incoming solar radiation is more direct as it is concentrated over a smaller area resulting in warmer temperatures. The sun’s rays striking the earth at higher latitudes is less direct and more scattered resulting in colder temperatures. This is why places closer to the equator are much warmer than places such as the north pole, even when it’s summer in the northern hemisphere. 

It’s impossible for the sun to heat the entire earth equally all at once, which is why the heat distribution across the globe is uneven. This differential heating creates large temperature differences between different parts of the earth, land and water. These differences in temperatures help drive our everyday weather.