The Earth’s Atmosphere Balances Energy and Sustains Life
- The Earth’s atmosphere is a mixture of gases, liquids, and solids that regulate energy flow and influence weather systems.
- It plays a vital role in supporting life and maintaining climate stability.
- Imagine Earth as a cozy greenhouse.
- The glass panels let sunlight in but trap warmth inside, creating a stable environment for plants to thrive.
Weather Happens in the Troposphere
Troposphere
The troposphere is the lowest layer of Earth’s atmosphere, extending from the surface up to about 8-15 kilometers (5-9 miles) in altitude, depending on the latitude. It contains around 75% of the atmosphere's mass.
- The troposphere contains most of the atmosphere’s water vapor, making it the primary layer for weather phenomena, such as clouds, wind, precipitation, and storms.
- Temperatures decrease by an average of 6.5°C per km with altitude.
Think of the troposphere as the "active" layer, where weather events like storms and rain occur due to water vapor and heat exchanges.
The Atmosphere Redistributes Solar Energy
Atmosphere
The atmosphere is an open energy system that receives solar radiation (insolation) from the Sun.
- The Sun emits energy, whereas the Earth receives it and either reflects it back to space or absorbs it and re-radiates it later.
- This energy drives global weather systems and climate patterns:
- Energy Absorption: Most solar energy is absorbed in tropical regions near the equator.
- Energy Redistribution: To maintain balance, wind and ocean currents move energy from warmer tropical regions to cooler polar regions.
The Energy Budget Maintains Climate Balance
Energy budget
The Earth’s energy budget refers to the balance between incoming solar energy and outgoing radiation.
- This balance ensures stable global temperatures and weather patterns.
- Components of the Energy Budget include:
- Incoming Solar Energy (insolation):
- 46% absorbed by the Earth’s surface.
- 22% drives the hydrological cycle (e.g., evaporation and condensation).
- 31% is reflected back into space by clouds, gases, and surfaces.
- Outgoing Energy:
- Heat is emitted as long-wave radiation, transferred back to the atmosphere.
- Processes like conduction (direct contact) and convection (air and liquid movement) facilitate heat transfer.
- Incoming Solar Energy (insolation):
Insolation is Affected by Latitude, Season, Clouds, and the Composition of the Atmossphere
Insolation
The energy received from the Sun mostly in the form of short-wave radiation. However, the Sun emits entire spectrum of electromagnetic waves.
- Variation Factors:
- Latitude: The Sun’s angle determines how much energy reaches the surface.
- Season: Energy varies with the tilt of the Earth’s axis.
- Cloud Cover: Thick clouds reduce incoming solar radiation, while clear skies allow more energy to reach the surface.
- Composition of the Atmosphere: Natural and human-induced air pollution (suspended particles in the air and gasses) impact the amount of sunlight reaching the surface.
When the Sun is high in the sky, about 40% of solar radiation is transmitted, delivering over 450 watts per m².
HintLess cloud cover means more radiation reaching the surface, influencing temperature and weather.
Long-Wave Radiation Balances Earth’s Heat
Long-wave radiation
Long-wave radiation refers to the energy re-emitted (re-radiated) by the Earth in a form of infrared (heat) after initial absorption of the short-wave solar radiation (mostly in the form of ultraviolet and visible light).
- Key Processes:
- During the day, incoming solar energy exceeds outgoing long-wave radiation, maintaining energy balance.
- At night, cloud cover traps long-wave radiation, reducing heat loss.
- Clear skies, however, lead to significant heat loss, especially in deserts.
- Impact of Clouds:
