Unit 4 - Atmosphere

Atmospheric Layers and Their Characteristics

Albedo

Albedo: The proportion of the incident light or radiation that is reflected by a surface.
High albedo surfaces, such as ice and snow, reflect more sunlight, while low albedo surfaces, like forests and oceans, absorb more.

Scattering

Scattering: The process by which particles and molecules deflect incoming solar radiation in different directions.
This can cause the sky to appear blue due to the scattering of shorter wavelengths of light by the atmosphere.

Greenhouse Effect

Greenhouse Effect: The warming of Earth's surface and lower atmosphere caused by the presence of greenhouse gases that trap heat radiating from Earth toward space.
This process keeps Earth's climate habitable.

Layers of the Atmosphere

Troposphere

Temperature: Decreases with altitude.
Characteristics: Weather occurs here, contains most of the atmospheric water vapor and clouds.
Key Feature: The lowest layer, closest to Earth's surface.

Stratosphere

Temperature: Increases with altitude.
Characteristics: Contains the ozone layer, which absorbs and scatters ultraviolet solar radiation.
Key Feature: Aircraft fly in the lower stratosphere to avoid turbulence.

Mesosphere

Temperature: Decreases with altitude.
Characteristics: The coldest layer, where meteors burn up upon entry.
Key Feature: Thin atmosphere, not suitable for human habitation.

Thermosphere

Temperature: Increases with altitude.
Characteristics: Contains the ionosphere, which is important for radio communication; auroras occur here.
Key Feature: High temperatures but low heat due to sparse molecules.

Exosphere

Temperature: Variable, as it merges with outer space.
Characteristics: Contains very few atmospheric particles, satellites orbit here.
Key Feature: The outermost layer, transitioning into space.

Surfaces and Sunlight

Absorption and Reflection

Absorb Sunlight: Forests, oceans, asphalt, soil.
Reflect Sunlight: Ice, snow, deserts, light-colored sand.

Atmospheric Pressure

Definition and Instruments

Definition: The force exerted by the weight of the atmosphere above a surface.
Instruments: Barometer (mercury or aneroid).

Sea Level vs. High Elevation

Atmospheric pressure is higher at sea level and decreases with elevation.

Electromagnetic Spectrum and Earth

Heat Absorption

Heats Earth's Surface: Visible light, infrared radiation.
Absorbed in the Atmosphere: Ultraviolet radiation (by ozone), infrared radiation (by greenhouse gases).
Scattered: Shorter wavelengths like blue and violet light.

Greenhouse Effect and Gases

Definition and Gases

Definition: The process by which certain gases in Earth's atmosphere trap heat.
Greenhouse Gases: Carbon dioxide (CO2), methane (CH4), water vapor (H2O), nitrous oxide (N2O), ozone (O3).

Causes of Wind

Mechanisms

Causes: Differences in atmospheric pressure due to temperature differences, leading to convection currents.
Relationship: Wind travels from high-pressure areas to low-pressure areas, influenced by convection currents and Earth's rotation.

Diagram of Earth's Wind Belts

Major Wind Belts

Major Wind Belts: Trade Winds, Westerlies, Polar Easterlies.

Latitudes of Pressure

High and Low Pressure:
Horse Latitudes: High pressure around 30° N/S.
Doldrums: Low pressure at the equator.
Subpolar Lows: Low pressure around 60° N/S.

Pressure and Cloud Formation

Low pressure areas are associated with cloud formation and precipitation due to rising air.

Land and Sea Breezes

Land Breeze

Land Breeze: Occurs at night; land cools faster than the sea, creating high pressure over land and low pressure over the sea, causing wind to blow from land to sea.

Sea Breeze

Sea Breeze: Occurs during the day; land heats faster than the sea, creating low pressure over land and high pressure over the sea, causing wind to blow from sea to land.

Coriolis Effect

Definition and Impact

Definition: The deflection of moving air and water due to Earth's rotation.
Effect on Winds: Causes winds to curve to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

Composition of the Atmosphere

Current Composition

Current Composition: Nitrogen (~78%), Oxygen (~21%), Argon (~0.9%), Carbon Dioxide (~0.04%), trace gases.

Changes Over Time

Increased oxygen levels due to photosynthesis, reduction of carbon dioxide levels, changes due to volcanic activity, and human influence.

Discussion questions

1 of 6

How does the albedo effect influence Earth's climate and temperature regulation?

Difficulty: Medium

Discuss the significance of the greenhouse effect in maintaining Earth's habitability.

Difficulty: Medium

What are the primary factors that cause wind, and how do they interact with Earth's rotation?

Difficulty: Hard

Explain the role of the ozone layer within the stratosphere and its importance to life on Earth.

Difficulty: Medium

How do land and sea breezes illustrate the principles of atmospheric pressure and temperature differences?

Difficulty: Easy

Analyze the composition of the atmosphere and its changes over time due to natural and human influences.

Difficulty: Hard