BaCCC/Video Summaries/Earth’s Energy Budget

Video Summary

Earth’s Energy Budget (6:59)

https://www.youtube.com/watch?v=el7ygWztQqA

• The Earth’s energy budget determines the globally average temperature of Earth, which governs whether we have a liveable planet or a cold, barren landscape.
• The essence of the Earth’s energy budget is the balance between incoming shortwave radiation from the sun and outgoing longwave radiation from the Earth itself.
• When the incoming and outgoing energy fluxes are in balance, then the Earth’s average temperature stays constant.
• When one or more parts of the energy budget change, an imbalance occurs and the Earth’s average temperature gets warmer or colder in response.
• Important processes in the Earth’s energy budget include the characteristics of the surface, atmospheric composition and the role of clouds.
• Bright surfaces reflect almost all of the incoming solar radiation back into space, while dark surfaces absorb the radiation and hold onto it as heat.
• The amount of incoming solar energy that is reflected is about 30%.
• Energy from the sun is emitted as shortwave radiation, and we experience this as a combination of visible light and radiant heat, while energy from Earth is emitted as longwave radiation.
• Most gases that make up the atmosphere are transparent to the incoming solar radiation and allow it to travel to the Earth’s surface, except ozone, which absorbs the ultraviolet portion of solar radiation and keeps us protected from this harmful type of radiation.
• The greenhouse effect occurs when heat energy is trapped in the atmosphere and causes a rise in the Earth’s temperature.
• Venus experienced a “runaway greenhouse effect,” causing it to become the hottest planet in our solar system, with a surface temperature of 872ºF (484ºC).
• Clouds can impact the amount of incoming solar radiation that reaches the Earth’s surface; they reflect about 24% of incoming radiation, reducing the amount of radiation that the surface receives and cooling the Earth.
• Determining the Earth’s energy budget comes down to the basic balance of incoming shortwave energy and outgoing longwave energy.