Composition of the Atmosphere & Radiative balance Flashcards
What are the three most abundant gases in Earth’s atmosphere?
Nitrogen (N₂) – 78.1%, Oxygen (O₂) – 20.9%, Argon (Ar) – 0.9%.
What are greenhouse gases (GHGs)?
Gases that trap infrared radiation (heat) in the atmosphere, contributing to the greenhouse effect.
Name four major greenhouse gases.
Carbon dioxide (CO₂), Methane (CH₄), Nitrous oxide (N₂O), Water vapor (H₂O).
What is residence time?
The average time a gas molecule stays in the atmosphere.
Which atmospheric gas has the longest residence time?
Nitrogen (N₂) – over 40 million years.
What are the main layers of the atmosphere (from lowest to highest)?
Troposphere, Stratosphere, Mesosphere, Thermosphere, Exosphere.
In which layer does weather occur?
Troposphere.
What is the significance of the stratosphere?
Contains the ozone layer, which absorbs harmful UV radiation.
What is the tropopause?
The boundary between the troposphere and the stratosphere.
Where does all atmospheric oxygen (O₂) come from?
Photosynthesis by plants and cyanobacteria.
What is the ozone layer and why is it important?
A region in the stratosphere where ozone (O₃) absorbs harmful UV radiation, protecting life on Earth.
What is the difference between “good” and “bad” ozone?
Good ozone (O₃) is in the stratosphere, blocking UV rays.
Bad ozone (O₃) is in the troposphere, contributing to smog and air pollution.
What human-made chemicals are responsible for ozone depletion?
Chlorofluorocarbons (CFCs).
What is radiative balance?
The balance between incoming solar radiation and outgoing infrared radiation from Earth.
What is blackbody radiation?
The concept that objects emit radiation based on their temperature.
How does Earth’s atmosphere interact with solar energy?
Visible light mostly passes through.
UV radiation is absorbed by O₂, O₃, and H₂O.
Infrared radiation is absorbed by GHGs (CO₂, CH₄, H₂O).
What would happen without the greenhouse effect?
Earth would be about 32°C (58°F) colder, making it uninhabitable.
What is the greenhouse effect?
The process by which greenhouse gases absorb and re-radiate infrared radiation, warming Earth’s surface.
Why is Venus much hotter than Earth?
Its thick atmosphere is 95% CO₂, creating an extreme greenhouse effect.
How does the greenhouse effect on Mars compare to Earth?
Mars has a weak greenhouse effect because its atmosphere is very thin.
What are aerosols and how do they affect climate?
Tiny particles in the atmosphere that can reflect sunlight (cooling effect) or absorb heat (warming effect).
What is the main driver of Earth’s climate?
The Sun.
What happens when the amount of greenhouse gases increases?
More infrared radiation is trapped, leading to global warming.
How do human activities contribute to climate change?
Burning fossil fuels increases CO₂ and CH₄, intensifying the greenhouse effect.
What is the significance of the radiation budget?
t determines Earth’s overall temperature by balancing absorbed solar energy and emitted infrared radiation.
