1. Heating the Atmosphere
Chapter 17.2
Heating the Atmosphere

2. Heat and temperature are not the same thing.
Heat is the energy transferred from one object to another because of differences in their temperature.
Temperature is the measure of the average kinetic energy (the energy of motion) of atoms or molecules in a substance.
As energy is transferred the molecules will move faster increasing temperature.

3. Energy Transfer as Heat
There are 3 ways energy is transferred as heat: conduction, convection, and radiation.
These are important for energy transferring energy between Earth’s surface and the atmosphere.

4. Conduction Conduction is the transfer of heat through direct contact.
Heat will flow from high temperature to low temperature.
If you put a pot on a burner that is on, the heat will transfer from the burner to the pot, heating the pot up. This is direct contact.
Different materials can conduct heat differently. Metals are good conductors. Air is a poor conductor of heat.
This is the least important way heat is transferred to or from the atmosphere.

5. Convection
Convection is the transfer of heat by circulation in a substance. This happens in fluids like the ocean or air. We also saw convection in the mantle.
When you heat a pot of water the water will warm up by convection. As the water is heated it becomes less dense so it will move to the top of the pan, the cooler water will sink to the bottom of the pan where it will become heated.
This is the main method of heat transfer in the atmosphere.

6. Electromagnetic Waves
The sun is the ultimate source of energy that makes weather. The sun gives off light and heat and ultraviolet rays.
These are all part of the electromagnetic spectrum.
The differences in the type of electromagnetic radiation is the wavelength of the waves.
Visible light is the only part of the electromagnetic spectrum you can see. The different colors have different wavelengths.

7. Radiation
Radiation is when heat moves in all directions from the source of it.
Radiant energy can travel through the vacuum of space. Our sun’s energy reaches us this way.
There are 4 laws of radiation:
1. All objects, at any temperature, emits radiant energy.
2. Hotter objects give off more total energy than colder objects.
3. The hottest radiating objects give off the shortest wavelengths
4. Objects that are good absorbers of radiation are good emitters also.

8. What Happens to Solar Radiation?
When radiation hits an objects 3 possible things happen:
1. Some of the energy is absorbed by the object – if you stand in the sun you absorb some of the sun’s energy (you warm up)
2. Substances like water and air are transparent to certain wavelengths of radiation – that means that radiation moves through these objects
3. Some radiation may bounce off the object without being absorbed or transmitted.

9. Reflection and Scattering
Reflection is when light bounces off an object.
Scattering is when light waves move in many different directions.
30% of the solar energy that reaches Earth is reflected back into space. This energy is not used to heat the Earth.
Small dust particles and gas molecules in the atmosphere cause this reflection and scattering.

10. Absorption
50% of the solar energy that hits the atmosphere reaches Earth’s surface and is absorbed.
The atmosphere absorbs longer wavelengths. Water vapor and carbon dioxide does most of this absorbing.
Absorbing solar energy causes a rise in temperature.
Greenhouse effect – this is the process of water vapor and carbon dioxide absorbing solar energy and then releasing it slowly, heating the Earth.