Teaching about the Sun's energy is supported by five key concepts:
a. Sunlight reaching Earth can heat the land, ocean, and atmosphere. Some of that sunlight is reflected back to space by the surface, clouds, or ice. Much of the sunlight that reaches Earth is absorbed and warms the planet.
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b. When Earth emits the same amount of energy as it absorbs, its energy budget is in balance, and its average temperature remains stable.
c. The tilt of Earth's axis relative to its orbit around the sun results in predictable changes in the duration of daylight and the amount of sunlight received at any latitude throughout a year. These changes cause the annual cycle of seasons and associated temperature changes.
d. Gradual changes in Earth's rotation and orbit around the sun change the intensity of sunlight received in our planet's polar and equatorial regions. For at least the last 1 million years, these changes occurred in 100,000-year cycles that produced ice ages and the shorter warm periods between them.
e. A significant increase or decrease in the sun's energy output would cause Earth to warm or cool. Satellite measurements taken over the past 30 years show that the sun's energy output has changed only slightly and in both directions. These changes in the sun's energy are thought to be too small to be the cause of the recent warming observed on Earth.
The Sun's energy drives the climate system
The sun warms the planet, drives the hydrologic cycle, and makes life on Earth possible. The amount of sunlight received on Earth's surface is affected by the reflectivity of the surface, the angle of the sun, the output of the sun, and the cyclic variations of Earth's orbit around the sun.
The basic science of solar energy and the role it plays for Earth's climate can be understood by middle school students, but the complexities of the Earth's energy balance remains an area of active scientific research. Thus, this topic is both elemental and complex.
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This principle is related to Energy Literacy Principle 2: Physical processes on Earth are the result of energy flow through the Earth system.
Show students the basic mechanics of the climate system
Understanding the role of solar radiation in the Earth's climate system can help us grasp important concepts such as: