Do Now: We all know that we cannot live on other planets, but why Do Now: We all know that we cannot live on other planets, but why? What makes Earth so unique that we can live on it?

Learning Objective: I will be able to explain how the layers of the atmosphere differ.

Success Criteria: I can explain how the composition of the atmosphere has changed. I can explain why the layers of the atmosphere change. I can interpret charts on the ESRT.

Composition of the Atmosphere: Has changed a lot over 4.6 billion years. Started from gases emitted from volcanoes. Oxygen began accumulating 2.5 billion years ago.

Composition of Air Nitrogen and Oxygen most abundant. Varies from time to time and place to place. Ex: rush hour and near factories and airports.

A layer of gases held close to the earth by the force of gravity. Our Atmosphere: A layer of gases held close to the earth by the force of gravity.

Layers of the atmosphere There are 4 layers in the atmosphere Troposphere Stratosphere Mesosphere Thermosphere

Question Why do you think the temperature falls and rises twice, going from lower to higher altitudes?

Troposphere: 10-20 km All weather occurs here Most water vapor and clouds Greenhouse gases located here Becomes colder with an increase in altitude

Composition of the Atmosphere: ESRT All other gasses: CO2, Ar, Methane etc

Troposphere Composition: Less than 2% Water vapor (0.1-4%) Argon gas (1%) Carbon Dioxide (0.04%) Trace gases

Pause… Why do you think most of the planets air is in the troposphere?

Stratosphere: 17-26 Km contains the Ozone Layer no precipitation

Ozone layer: Ozone (O3) absorbs most of the UV radiation from the sun and filters its rays This UV absorbtion causes it to heat up the part of the stratophere that’s closer to the sun (farthest from Earth)

Mesosphere: 80 Km Area where meteors are usually burnt up

Thermosphere (Ionosphere) 110 Km Thinnest Space shuttle orbits here

Aurora Borealis  A glow in the night sky produced in the upper atmosphere by ionized particles from the solar wind interacting with Earth’s magnetic field.

The aurora borealis occurs in which of the following parts of the atmosphere? Troposphere Thermosphere Mesosphere Hydrosphere Stratosphere

B Thermosphere (ionosphere)

The atmosphere is warmed as gases such as water vapor and carbon dioxide absorb the infared heat radiated from the earth. This process is best described as Ozone depletion The green house effect Biomagnification Ionization Convection

B= As the sun’s light passes through the atmosphere it strikes the solid earth. The earth with its soil, water, buildings, asphalt and concrete absorb this radiant energy. This energy is then radiated back into the atmosphere as infrared radiation. This radiation can be reflected back into the atmosphere (the greenhouse effect) or pass back into space

Summary Exit Quiz