APES CHAPTER 4

climate

The average weather that occurs in a given region over a long period of time.

Weather

The short-term conditions of the

atmosphere in a local area, which include temperature, humidity, clouds, precipitation, and wind speed.

Troposphere

A layer of the atmosphere closest

to the surface of Earth, extending up to approximately 16 km (10 miles).

Stratosphere

The layer of the atmosphere

above the troposphere, extending roughly 16 to 50 km (10-31 miles) above the surface of Earth.

Albedo

The percentage of incoming sunlight reflected from a surface.

Albedo

The albedo of a surface is the percentage of the incoming solar energy that it reflects. Snow and ice reflect much of the solar energy that they receive, but darker objects such as forests and asphalt paving reflect very little energy, which means that they absorb most of the solar energy that strikes them

Saturation point

The maximum amount of water

vapor in the air at a given temperature.

Adiabatic cooling

The cooling effect of reduced

pressure on air as it rises higher in the atmosphere and expands.

Adiabatic heating

The heating effect of increased

pressure on air as it sinks toward the surface of Earth and decreases in volume.

Latent heat release

The release of energy when

water vapor in the atmosphere condenses into liquid water.

Atmospheric convection current

Global patterns of air movement that are initiated by the unequal heating of Earth.

Hadley cell

A convection current in the atmosphere that cycles between the equator and 30°N and 30°S.

Atmospheric currents

Warming at Earth's surface

causes air to rise up into the atmosphere where it

experiences lower pressures, adiabatic cooling, and latent heat release. The cool air near the top of the atmosphere is then displaced horizontally before it sinks back to Earth. As it sinks,

the air experiences adiabatic heating and then moves horizontally along the surface of Earth to complete the cycle.

Intertropical convergence zone (ITCZ)

The latitude that receives the most intense sunlight, which causes the ascending branches of the two Hadley cells to converge.

Polar cell

A convection current in the atmosphere, formed by air that rises at 60°N and 60°S and sinks at the poles, 90°N and 90°S.

Ferrell cell

A convection current in the atmosphere that lies between Hadley cells and polar cells.

Coriolis effect

The deflection of an object's path due to the rotation of Earth.

Hadley cells

Hadley cells are atmospheric

convection currents that operate between the equator and 30°N and 30°S. Solar energy warms humid air in the tropics. The warm air rises and eventually cools below its saturation point. The water vapor it contains condenses into clouds and precipitation. The air, which now contains little moisture, sinks to Earth's surface at approximately 30°N and 30°S. As the air descends, it is warmed by adiabatic heating. This descent

of hot, dry air causes desert environments to develop at those latitudes.

Rain shadow

A region with dry conditions found on the leeward side of a mountain range as a result of humid winds from the ocean causing precipitation on the windward side.

Gyre

A large-scale pattern of water circulation that moves clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere.

Upwelling

The upward movement of ocean water toward the surface as a result of diverging currents.

Thermohaline circulation

An oceanic circulation pattern that drives the mixing of surface water and deep water.

El Niño-Southern Oscillation (ENSO)

A reversal of wind and water currents in the South Pacific.

Terrestrial biome

A geographic region categorized by a particular combination of average annual temperature, annual precipitation, and distinctive plant growth forms on land.

Aquatic biome

An aquatic region characterized by a particular combination of salinity, depth, and water flow.

Tundra

A cold and treeless biome with low-growing vegetation.

Boreal forest

A forest biome made up primarily of coniferous evergreen trees that can tolerate cold winters and short growing seasons.

Temperate rainforest

A coastal biome typified by moderate temperatures and high precipitation.

Temperate seasonal forest

A biome with warm summers and cold winters with over 1 m (39 inches) of precipitation annually.

Woodland/shrubland

A biome characterized by hot, dry summers and mild, rainy winters.

Temperate grassland/cold desert

A biome characterized by cold, harsh winters, and hot, dry summers.

Tropical rainforest

A warm and wet biome found between 20°N and 20°S of the equator, with little seasonal temperature variation and high precipitation.

Tropical seasonal forest/savanna

A biome marked by warm temperatures and distinct wet and dry seasons.

Subtropical desert

A biome prevailing at approximately 30°N and 30°S, with hot temperatures, extremely dry conditions, and sparse vegetation.

Littoral zone

The shallow zone of soil and water in lakes and ponds where most algae and emergent plants grow.

Limnetic zone

A zone of open water in lakes and ponds.

Phytoplankton

Floating algae.

Profundal zone

A region of water where sunlight does not reach, below the limnetic zone in very deep lakes.

Benthic zone

The muddy bottom of a lake, pond, or ocean.

Oligotrophic

Describes a lake with a low level

of productivity.

Mesotrophic

Describes a lake with a moderate

level of productivity.

Eutrophic

Describes a lake with a high level of productivity.

Freshwater wetland

An aquatic biome that is submerged or saturated by water for at least part of each year, but shallow enough to support emergent vegetation

Salt marsh

A marsh containing nonwoody

emergent vegetation, found along the coast in temperate climates.

Mangrove swamp

A swamp that occurs along tropical and subtropical coasts, and contains salt tolerant trees with roots submerged in water.

Intertidal zone

The narrow band of coastline

between the levels of high tide and low tide.

Coral reef

The most diverse marine biome on Earth, found in warm, shallow waters beyond the shoreline.

Coral bleaching

A phenomenon in which algae inside corals die, causing the corals to turn white.

Open ocean

Deep ocean water, located away

from the shoreline where sunlight can no longer reach the ocean bottom.

Photic zone

The upper layer of ocean water in the ocean that receives enough sunlight for photosynthesis.

Aphotic zone

The deeper layer of ocean water

that lacks sufficient sunlight for photosynthesis.

Chemosynthesis

A process used by some bacteria in the ocean to generate energy with methane and hydrogen sulfide.

Differential heating of Earth

Tropical regions near the equator receive more solar energy than mid-latitude and polar regions, where the Sun's rays strike Earth's surface at an oblique angle.

Earth's seasons

Because Earth's axis of rotation is tilted 23.5°, the latitude that receives the most direct rays of the Sun and the most hours of daylight changes throughout the year

as Earth orbits the Sun. Thus Earth's tilt produces predictable seasons. This diagram illustrates the pattern of seasons in the Northern Hemisphere.

Prevailing wind patterns.

Prevailing wind patterns around the world are produced by a combination of atmospheric convection currents and the Coriolis effect.

The El Niño-Southern Oscillation.

In a normal year, trade winds push warm surface waters away from the coast of South America and promote the upwelling of water from the ocean bottom. (b) In an El Niño year, trade winds weaken or reverse direction, so warm waters build up along the west coast of Peru.

Biomes

Biomes are categorized by particular combinations of average annual temperature and annual precipitation.

Climate diagrams

Climate diagrams display monthly temperature and precipitation values, which help determine the productivity of a biome.

Permafrost

An impermeable, permanently frozen layer of soil.