# Lesson 3.2 Local climate drivers

I am a bit confused about the part about the angle of the slope affecting the amount of incoming solar radiation received. Wouldn’t this example with the equator receiving sunlight in a perpendicular direction only be true during spring and autumn? So calculating the “optimum” angle as equal to the latitude would only work during these precise times, and at other times in the year you would have to subtract whatever angle the latitude is where the sun’s rays are perpendicular, which was explained (very nicely!) in video 3.1. Is this right or is there something I am missing?

Perhaps it is averaged over the year, so the slope that gets the most sun over the course of a whole year is equal to the latitude?

1 Like

Hey @Kristina. After some head scratching and a (bad) drawing, I concur. Unless I’m missing something, the slope == latitude → max solar radiation only applies when the sun is above the equator, in spring and fall. At other times, the tilt of the Earth with respect to the Sun would need to be taken into account it seems.

2 Likes

Hey @manoel @Kristina, thanks for bringing this up, it was confusing me as well. Follow up question: is my understanding correct that the situation/configuration @manoel drew happens only twice a year (at equinoxes)? The rest of the time the sun rays (those that are hitting the surface of the Earth perpendicularly) are sort of wobbling up and down between the tropics?!

2 Likes

That’s my understanding as well.

2 Likes