Some part of the United States have different weather during different times of the year. Cold and snowy winters may change to hot and humid summer. In other parts of the country, it is always cold at earth's poles. These places have differrent climates, or usual weather patterns for an area. The most important reason for the different climates is the tilt, or slant, of Earth's axis as Earth orbits, or circles, the Sun.
Earth's axis is the imaginary line tgat goes through the middle of Earth. It goes from the North Pole to the South Pole. For half of the year. or half of Earth's orbit, the northern half of Earth tilts toward the Sun. For the other half of the year, the southern half tilts toward the Sun. More direct light and heat reach the half of Earth that is tilted toward the sun. so it is warmer on that half of Earth,the seasons is summer. The half of Earth that is tilted away from the Sun receives less direct heat and light. The seasons on that half of Earth is winter. summer starts in June in the northern half of the wolrd, and summer starts in December in the southern half of the world.
The Sun's light shines on earth in rays, or lines of light. These rays always form an angle with the surface of Earth. In the tronics along the equater. this angle does not change very much throughout the year. The tropics get direct sunlight all year and are always hot. Instead of summer and winter, the tropics may have a dry season or a wet season, depending on how much rain falls.
The angle of the Sun's rays the North and South Poles makes these places cold. In the summer, when a pole is tilted toward the Sun, it may get up to 24 hours of sunlight a day. However, the angle of the rays is very sharp. Because of this, the heat of the rays is not very strong. In the winter. when the pole is tilted away from the Sun, the rays of the Sun hit the pole for only a few hours each day. During some winter days, the rays may not hit the pole at all. Winters at the poles are dark and very cold. Without the summer months in these and other cold regions, plants and animals probably could not survive. The length and warmth of the summer in any particular region determine what kinds of plants and animals can occupy that region.