Latitude affects climate because the closer any certain area is to the equator, that area will have a higher overall temperature (3 zones; polar, temperature, tropical)
Latitude affects climate because the farther away you are from the equator, the colder it is. This is due to the fact that the earths curvature causes the sun's rays to be more concentrated at the equator and more spread out. So, farther north, in the Arctic, the sunlight is less concentrated as it is spread out over a larger area of land. In Brazil, for example, it is closer to the equator, so the sunlight would be much more concentrated, therefore warmer.