Earth's Atmosphere Flashcards

Study Notes

Composition of Earth's Atmosphere

Current atmospheric composition: 78% Nitrogen, 21% Oxygen, 1% other gases (Argon, Carbon Dioxide, Water Vapor).
Early atmosphere was drastically different and primarily created by volcanic outgassing.

Early Atmosphere Characteristics

Early atmosphere lacked atmospheric Oxygen.
Absence of rust in iron fossil evidence indicates negligible oxygen prior to 2.3 billion years ago.

Oxygen-Producing Lifeforms

Cyanobacteria were the first known oxygen-producing bacteria.
Fossils date back several hundred million years before oxygen abundance created red beds.

Layers of Earth's Atmosphere

Composed of five main layers: Troposphere, Stratosphere, Mesosphere, Thermosphere, Exosphere.

Troposphere

The lowest atmospheric layer extending from the ground to 7.5 miles up.
Contains 75-80% of atmospheric gases and is where most weather occurs.
Atmospheric pressure decreases with elevation; at sea level, pressure is about 14 pounds per square inch.

Stratosphere

Lies above the Troposphere, from approximately 7.5 to 25 miles above the ground.
Houses the Jet Stream, which consists of high-speed wind belts influencing weather patterns in lower states.
Contains the ozone layer, which protects life from harmful UV radiation; degraded by CFCs (mostly banned).

Mesosphere

Middle layer of the atmosphere, approximately 25 to 55 miles in altitude.
Site where meteors begin to burn upon entering the atmosphere.

Thermosphere

Uppermost layer, ranging from about 55 miles to over 300 miles.
Characterized by extremely high temperatures due to solar radiation interacting with atmospheric gases.
Contains the Ionosphere, where charged particles exist; also the location of Aurora Borealis phenomena.

Exosphere

The outermost layer of Earth's atmosphere leading into outer space.

Types of Heat Transfer

Radiation: Movement of energy through wave motion.
Conduction: Energy transfer through direct touch.
Convection: Circular movement of heat in fluids.

Global Winds

Wind belts function as massive convection currents, redistributing heat and weather patterns globally.
Prevailing Westerlies primarily influence weather in the lower 48 states, including Virginia.

Division of Atmospheric Layers

Layers are categorized based on thermal properties, chemical composition, movement, and density.

Atmospheric Boundaries

"Pauses" denote boundaries where significant changes occur, marked by shifts in temperature, chemical makeup, or density.

Description

Explore the essential elements of Earth's atmosphere with these informative flashcards. Learn about its composition and the differences between the current and early atmosphere. Perfect for students looking to enhance their understanding of atmospheric science.