1. Energy from the Sun
Sun’s energy travels 148 million km to Earth in only 8 minutes
Earth receives less than one-billionth of the Sun’s energy
Reaches Earth through the process of radiation
Radiation is the transfer of energy by electromagnetic waves
99% of the radiant energy from the Sun consists of…
44% Visible light, 7% ultraviolet light, and 49% infrared radiation

2. Visible Light
Majority of sunlight that reaches Earth’s surface is visible light
Atmosphere allows visible light to pass through

3. Near-Visible Wavelengths
Ultraviolet (UV) and infrared radiation (IR) are just beyond our range of visibility
UV light have short wavelengths and can break chemical bonds
Can cause sunburn and skin cancer
IR have longer wavelengths
IR can be seen thermal energy or warmth
Earth absorbs energy from the Sun and then radiates it into the atmosphere as IR

4. Energy on Earth Absorption
Gases and particles in the atmosphere absorb about 20% of incoming solar radiation
Ultraviolet Light
Oxygen, ozone, and water vapor absorb
Infrared Radiation
Water and carbon dioxide absorb some in the troposphere
Visible Light
Earth’s atmosphere does not absorb

5. Energy on Earth cont’d. Reflection
Bright surfaces, especially clouds, reflect incoming radiation
Some radiation reaches Earth’s surface and then is reflected
Most commonly by snow-covered, icy, or rocky surfaces
In total, about 50% of Sun’s radiation is absorbed by Earth’s surface

6. Radiation balance
There is a balance between the amount of incoming radiation from the Sun and outgoing radiation from Earth
Land, water, plants, and other organisms absorb solar radiation
The radiation is then re-radiated, or bounced back, into the atmosphere as infrared radiation
Overall, Earth receives and re-radiates out the same amount of solar radiation

7. Radiation Balance