Key Idea: The annual rise and fall of air temperature at any place and the differences in the rise and fall in air temperatures between two places are explained by the amount of solar energy that reach those places.

Students are expected to know that:

  1. From late December to late June at places north of the tropical region, both the number of daylight hours and the maximum height of the sun in the sky (intensity of sunlight) gradually increases a little bit each day, which means that the amount of solar energy transferred to those places over the course of each day gradually increases. The gradual increase in solar energy transferred leads to a gradual increase in air temperature from December to June at those places. The same pattern occurs at places south of the tropical region from late June to late December.
  2. From late June to late December at places north of the tropical region, both the number of daylight hours and the maximum height of the sun in the sky (intensity of sunlight) gradually decreases, which means that the amount of solar energy transferred to those places over the course of each day gradually decreases. The decrease in solar  energy leads to a gradual decrease in air temperature from June to December. The same pattern occurs at places south of the equator between late December and late June.
  3. Both the number of daylight hours and maximum height of the sun in the sky (intensity) change more over the course of a year the farther a place is north or south of the tropical region, which means that the amount of solar energy transferred to a place changes more over a year the farther the place is from the tropical region . Because the amount of solar energy transferred to a place influences the air temperature at that place, there is a very small rise and fall in air temperature over the course of a year at the tropical region, and the farther a place is north or south of the tropical region, the larger the rise and fall in air temperature over the course of a year.

Boundaries:

  1. Students do not need to know the pattern of changes in solar energy over a year within the tropical region.