Chapter 7, Lesson 2 Notes
*Nearly all of the energy in Earth’s atmosphere comes from the sun and travels as electromagnetic waves, a form of energy that can move through the vacuum of space.
*Electromagnetic waves can be classified according to wavelength.
*Most of the energy from the sun travels to Earth in the form of visible light and infrared radiation.
*A smaller amount arrives as ultraviolet radiation.
*Visible light includes all colors of the rainbow. The different colors are different wavelengths.
*The direct transfer of energy by electromagnetic waves is called radiation.
*Infrared radiation has wavelengths longer than red light, it’s invisible to humans, but can be felt as heat.
*The sun also gives off ultraviolet radiation, which is an invisible form of energy with wavelengths shorter than violet light.
*Some sunlight is absorbed or reflected by the atmosphere before it can reach the surface, the rest of the sunlight passes through the atmosphere to Earth’s surface.
*Some ultraviolet radiation is absorbed by the ozone layer. Infrared radiation passes farther before some is absorbed by water vapor and carbon dioxide.
*In the troposphere, clouds reflect some sunlight back into space.
*Earth’s surface radiates some energy back into the atmosphere as infrared radiation.
*Some travels back into space, but much is absorbed by water vapor, carbon dioxide, and other gases.
*These gases hold heat in the atmosphere in a process called the greenhouse effect, which keeps Earth at a comfortable temperature. Human activities may be altering this process.
*Energy provided by the sun influences global winds and creates temperature differences among Earth’s air, water, and land.
*Global winds are created by the unequal heating of Earth’s surface over a large area.
*Because of Earth’s spherical shape, rays from the sun strike directly at the equator but hit the poles at a lower angle. As a result, temperatures near the poles are much lower than near the equator.
*The differences between the equator and the two poles produce giant convection currents in the atmosphere.
*Surface winds blow from the poles toward the equator. Higher in the atmosphere, winds flow from equator to poles.
*The way Earth’s rotations make winds curve is called the Coriolis effect.
*Because of the Coriolis effect, global winds in the Northern Hemisphere gradually turn toward the right.
*Land heats and cools more rapidly than water.
*Also, land can heat to higher temperatures than water can.
*Land can also cool to lower temperatures than water can.
*Heating and cooling of Earth’s land and water directly affect the air temperature above these surfaces. This process helps create winds.