Unit 2: Atmosphere // Visuals

Animation(s)

Carbon cycle imbalance: Natural processes cycle carbon dioxide through the atmosphere. The burning of fossil fuels increases the concentration of carbon dioxide above historic levels. View animation
Change in atmospheric carbon dioxide levels: Carbon dioxide levels in the atmosphere increased overall from 1955-2005, but levels fluctuate between seasons and during the day. View animation
The effects of "greenhouse gas": "Greenhouse gases" help to regulate the Earth's temperature. When out of natural balance, they restrict the reflection of infrared energy back into space, trapping heat in the atmosphere. View animation
The maximum velocity of tropical cyclones (hurricanes): The maximum velocity of hurricanes is restricted by natural limits of vertical temperature gradient, evaporation, friction, and heat transfer of sea spray. View animation

Photograph(s)

Farm abandonment (1850) and hardwood forest regrowth (1930) in central New England: Forest regrowth on lands that were previously farmed or logged is an important sink for atmospheric carbon. View image
Tall tower monitoring station for atmospheric sampling: Researchers use tall towers to obtain air samples that are not affected by local sources and sinks such as vegetation or nearby traffic. View image

Graphic(s)

Atmospheric water vapor mean, 1988-1999: Because Earth is warmest near the equator, atmospheric water vapor levels are highest in tropical regions. View image
Circulation of air around regions of high and low pressure in the Northern Hemisphere: Air moves toward low-pressure regions and away from high-pressure regions. The Coriolis force deflects these air masses in opposite directions around high and lows. View image
Conditional instability: When conditional instability exists, air parcels are stable if they are dry and unstable if they are saturated. Conditional instability can help to generate storms by causing parcels of moist air to rise and form towering clouds. View image
Coriolis force: The Coriolis force is created by Earth's rotation, which deflects air masses as they move over long distances. It is strongest near the poles and nonexistent at the equator. View image
Earth-atmosphere energy balance: Energy received from the Sun balances the energy that Earth loses back into space, maintaining a stable average temperature. View image
Effects of cirrus and cumulus clouds on Earth's energy balance: Cirrus clouds permit most of the sunlight that reaches them to pass through to Earth's surface, while thicker cumulus clouds reflect much of the sunlight that strikes them back into space. Both types block some of the heat radiating from Earth, warming the planet's surface. View image
General circulation of the atmosphere: Differential heating of Earth produces distinct patterns of rising and descending air masses, winds, and storms in well-defined cells around the globe. View image
Geostrophic flow: Geostrophic flow is more common in the upper atmosphere than at the surface, where friction between air and land slows the movement of air parcels. View image
Global circulation and climate: Each hemisphere has a number of distinct climate zones with characteristic weather patterns. View image
Hurricane wind patterns: Hurricane wind speeds range from 74 miles per hour (the minimum for a Category 1 storm on the Saffir/Simpson scale) to more than 155 miles per hour for Category 5 storms. View image
Importance of human-produced greenhouse gases: CO₂ is the most important anthropogenic greenhouse gas, but other gases also make significant contributions to climate change. Other pollutants, such as fine particulates, also affect how much solar radiation is retained in Earth's atmosphere. View image
Mid-latitude cyclones along the polar front: Mid-latitude cyclones occur when warm and cold air masses collide around a center of low pressure. View image
Relative proportions of inorganic forms of CO₂ dissolved in seawater: Under current conditions bicarbonate is the most abundant form of CO₂. All three forms are important for biological processes carried out by marine organisms. The green arrows in this diagram show the range of pH (7.5 to 8.5) that is likely to be found in the oceans now and in the future. View image
Sea breeze: Sea breezes are caused by temperature differences between land at the surface and adjoining water, which cause air to flow in opposite directions during the day and at night. View image
Structure of the atmosphere: Atmospheric pressure decreases exponentially as altitude increases, while temperature rises with altitude in some layers and decreases in others. View image
The electromagnetic spectrum: The Sun is much hotter than Earth, so it emits radiation at shorter wavelengths. The solar spectrum x 10^-6 applies at the surface of the Sun, not at Earth's orbit. Solar energy flux is lower by a factor of 50,000 at Earth's orbit. View image
The global carbon cycle: Carbon cycles constantly between land, oceans, and the atmosphere, although its residence time in various reservoirs can vary greatly. Black arrows in this image show natural fluxes and red arrows show anthropogenic contributions. View image
Winds around highs and lows: Sinking air near high-pressure systems inhibits the formation of clouds, so highs are associated with clear, dry weather. Rising air near low-pressure systems produces clouds and rain. View image

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