Lecture 7: Earth's energy budget/balance 2

Question 1

ALBEDO

Answer 1

Albedo is the percentage of radiation returning from a surface compared to that which strikes it,

in other words,
the ratio between reflected radiation to incoming radiation.

Question 2

MODES OF THERMAL ENERGY TRANSFER

Answer 2

• Conduction: through contact
• Convection: gases & fluids
• Radiation: works also in vacuum

Question 3

THE GREENHOUSE EFFECT

Answer 3

Greenhouse gases are atmospheric gases which absorb thermal radiation emitted by the Earth’s surface.

This blanketing effect leads to an increase in surface temperatures.

Question 4

ABSORPTION OF INFRARED ENERGY BY GREENHOUSE GASES

Answer 4

• Thermal radiation emitted by Earth
• Different absorption bands for individual greenhouse gases
• Note the “atmospheric windows” between 8 and 14 μm, apart from the ozone
band and in the absence of clouds
• Dashed lines are radiation curves of black body at different temperatures