How are Earth’s seasons related to the way Earth tilts in space?

Learn how Earth's tilt creates seasons, impacting daylight and temperature. Understand your world!

What conditions are affected by the tilt of Earth's axis? Earth’s axis is tilted at 23.5°. Earth’s axis always points toward the North Star as Earth revolves around the sun. Thus, during each revolution, the North Pole may be tilted toward the sun or away from the sun, as seen below. When the North Pole is tilted toward the sun, the Northern Hemisphere has longer periods of daylight than does the Southern Hemisphere. When the North Pole is tilted away from the sun, the opposite is true. Temperature The angle at which the sun’s rays strike each part of Earth’s surface changes as Earth moves in its orbit. When the North Pole is tilted toward the sun, the sun’s rays strike the Northern Hemisphere more directly. Thus, the region receives a higher concentration of solar energy and is warmer. When the North Pole is tiltedaway from the sun, the sun’s rays strike the Northern Hemisphere less directly. When the sunlight is less direct, the solar energy is less concentrated and the region is cooler.The spherical shape of Earth also affects how the sun warms up an area. Temperatures are high at point A in the diagram. This is because the sun’s rays hit Earth’s surface at a right angle and are focused in a small area. Toward the poles, the sun’s rays hit Earth’s surface at a lesser angle. Therefore, the rays are spread out over a larger area and the temperatures are cooler. Which location on the illustration of Earth below receives more direct rays from the sun? A B They receive equal amounts. Daylight Hours All locations on Earth experience an average of 12 hours of light a day. However, the actual number of daylight hours on any given day of the year varies with location. Areas around Earth’s equator receive about 12 hours of light a day. Areas on Earth’s surface that are tilted toward the sun have more hours of daylight. These areas travel a longer path through the lit part of Earth than areas at the equator. Areas on Earth’s surface that are tilted away from the sun have less than 12 hours of light a day. These areas travel a shorter path through the lit part of Earth, as shown below. Midnight Sun When it is summer in the Northern Hemisphere, the time in each day that it is light increases as you move north of the equator. Areas north of the Arctic Circle have 24 hours of daylight, called the “midnight sun,” as seen in the photo. At the same time, areas south of the Antarctic Circle receive 24 hours of darkness, or “polar night.” When it is winter in the Northern Hemisphere, conditions in the polar areas are reversed. What Causes Seasons? Most locations on Earth experience seasons. Each season is characterized by a pattern of temperature and other weather trends. Near the equator, the temperatures are almost the same year-round. Near the poles, there are very large changes in temperatures from winter to summer. We experience seasons due to the changes in the intensity of sunlight and the number of daylight hours as Earth revolves around the sun. So, both the tilt of Earth’s axis and Earth’s spherical shape play a role in Earth’s changing seasons.