You see, an object like the Earth is constantly receiving as well as emitting energy. As long as it is receiving more energy than it is emitting, it will continue to warm. Take the Earth’s surface on a typical day for instance. During the day, the sun’s energy is received at the earth’s surface to warm temperatures. The warmest temperatures don’t occur at noon when the sun’s angle is at its highest however. The warmest temperatures usually occur several hours later during the late afternoon hours. That is because heating is cumulative. Heating will continue to occur as long as more energy is being received than is being emitted. Just the opposite is true at night. You don’t get your coolest temperatures in the middle of the night, but instead during the early morning hours.

This same concept is applied to the seasons. Your coldest temperatures don’t occur on the first day of winter when the sun angle is lowest, but rather a month or two later while the earth is still emitting more energy (latent heat) than it is receiving. Therefore your hottest temperatures don’t occur when your sun angle is at its highest, but rather a month or two later while the earth’s surface is still receiving more energy than it is emitting.