1. Aim: What is the atmosphere and how does heat travel through it?
Notepack 33
Aim: What is the atmosphere and how does heat travel through it?
Do Now: Write down why the atmosphere is important.

2. What is the Atmosphere?
The atmosphere is a layer of gases that surrounds a planet.
The Earth's atmosphere has 3 main functions:
Support life- If the atmosphere contains oxygen, it may support organisms.
Protect – The Earth’s Atmosphere reflect and/or absorb dangerous materials given off from the Sun like radiation.
Controls weather – By trapping heat and water vapor, the atmosphere can produce weather.

3. What is the Atmosphere Composed of?

4. The Layers of the Atmosphere
The atmosphere is divided by 4 major layers:
The Troposphere – closest to the ground. Where weather occurs.
The Stratosphere – helps absorb UV Radiation.
The Mesosphere – Where most meteors burn up.
The Thermosphere – The outermost layer – next layer is SPACE!!

5. How are these layers formed?
The atmosphere can be divided vertically into four layers based on temperature
The troposphere is the bottom layer of the atmosphere where temperature decreases with an increase in altitude.
The stratosphere is the layer of the atmosphere where temperature remains constant to a height of about 20 kilometers. It then begins a gradual increase until the stratopause.
The mesosphere is the layer of the atmosphere immediately above the stratosphere and is characterized by decreasing temperatures with height.
The thermosphere is the region of the atmosphere immediately above the mesosphere and is characterized by increasing temperatures due to the absorption of very short-wave solar energy by oxygen.

7. Some Characteristics of the Atmosphere – Air Pressure
Air pressure refers to the weight (pressure) of all the air molecules above something.
Has you move higher in the atmosphere (gain altitude) the air pressure drops.
There is less air molecules as you move higher in the atmosphere – It’s harder to breath.

8. The Relationship Between the Atmosphere and the Sun
The Sun release some energy in the form of heat and light.
When this heat hits the Earth it causes the temperature for the Earth (the ground) to increase.
There are 2 factors that determines how much heat an area of the Earth receives.
The Earth’s rotation – the never ending cycle of day and night
The Earth’s tilt and its revolution around the Sun – the constant change in the Sun’s angle to the ground. (insolation)

9. How does the Sun heat up the Atmosphere?
The heat from the Sun can be transferred to the atmosphere in three ways:
Conduction
Convection
Radiation

10. Energy Transfer as Heat - Conduction
Conduction is the transfer of energy (heat) through a material.
An object may be heated at one end and over time the heat will spread to the cooler parts of the object.

11. Energy Transfer as Heat - Convection
Convection is the transfer of energy (heat) through a liquid or gas as the results changes in density of the heated object.
As the object is heated its density becomes less, so the object rises; but when is cools the object becomes more dense and the object sinks.

12. Energy Transfer as Heat - Radiation
Radiation is the transfer of energy (heat) through space by electromagnetic waves that travel out in all directions.
Unlike conduction and convection, which need material to travel through, radiant energy can travel through the vacuum of space.
When radiation strikes an object, there usually are three different results.
Some energy is absorbed by the object
Substances, such as water and air, are transparent to certain wavelengths of radiation so the heat moves through it.
Some radiation may bounce off the object without being absorbed or transmitted.

14. Energy Transfer as Heat – Radiation cont.
The color of an object can determine how much heat is absorbed.
Dark colors tend to absorb more heat than lighter colors.
Lighter colors tend to reflect heat more than darker colors.
The texture of an object can determine how light is reflected.
Surfaces that are smooth tend to reflect more heat than surfaces that are rough.
When radiation strikes an object, there usually are three different results.
Some energy is absorbed by the object
Substances such as water and air are transparent to certain wavelengths of radiation.
Some radiation may bounce off the object without being absorbed or transmitted.

15. The poles are covered with Ice-
This icy landscape is light in color and has a smooth surface, so a lot of heat is being reflected back to space. So the temperature is cold.
The rainforest are covered with trees- This vegetative landscape is dark in color and has a rough surface, so a lot of heat is being absorbed. So the temperature is warm.