climate: The average weather that occurs in a given
region over a long period of time.
Regional differences in temperature and precipitation
unequal heating of Earth by the Sun, atmospheric convection
currents, the rotation of Earth, Earth’s orbit around the Sun on a tilted
axis, and ocean currents.
troposphere: A layer of the atmosphere closest to the surface of
Earth, extending up to approximately 16 km (10 miles) and
containing most of the atmosphere’s nitrogen, oxygen, and water
stratosphere: The layer of the atmosphere above the troposphere,
extending roughly 16 to 50 km (10–31 miles) above the surface of Earth.
Beyond the stratosphere are the mesosphere, the
thermosphere, and farthest from Earth, the exosphere
thermosphere is also interesting because it contains charged gas molecules that, when hit by solar
energy, begin to glow and produce light
northern lights, or aurora borealis & southern lights, or aurora australis
Unequal heating of Earth
albedo: The percentage of incoming
sunlight reflected from a surface.
PROPERTIES OF AIR Air has four properties that determine how it circulates in
the atmosphere: density, water vapor capacity, adiabatic heating or cooling, and
latent heat release.
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.
FORMATION OF CONVECTION CURRENTS
Hadley cell: A convection current in the atmosphere that
cycles between the equator and 30° N and 30° S.
intertropical convergence zone (ITCZ): An
area of Earth that receives the most intense
sunlight; where the ascending branches of
the two Hadley cells converge.
polar cell: A convection cell in the atmosphere,
formed by air that rises at 60° N and 60° S and sinks at
the poles, 90° N and 90° S.
GYRES Global prevailing wind patterns play a major role in determining the direction in which ocean
surface water moves away from the equator
UPWELLING Ocean currents also help explain why some regions of the ocean support highly
THERMOHALINE CIRCULATION Another oceanic circulation pattern, thermohaline circulation, drives
the mixing of surface water and deep water. Scientists believe this process is crucial for moving heat
and nutrients around the globe.
HEAT TRANSPORT Ocean currents can affect the temperature of nearby landmasses.
El NiÑo–Southern Oscillation (ENSO): The periodic changes in winds and ocean currents, causing
cooler and wetter conditions in the southeastern United States and unusually dry weather in
southern Africa and Southeast Asia.
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.
Aquatic biomes are categorized by salinity,
depth and water flow
Aquatic biomes fall into two broad categories:
freshwater and marine. Freshwater biomes include
streams, rivers, lakes, and wetlands. Saltwater biomes,
also known as marine biomes, include shallow marine
areas such as estuaries and coral reefs as well as the
photic zone: The upper layer of water in the ocean that receives
enough sunlight for photosynthesis.
aphotic zone: The 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.
Streams and Rivers are characterized by flowing fresh water that may
originate from underground springs or as runoff from rain or melting
snow. Streams (also called creeks) are typically narrow and carry
relatively small amounts of water. Rivers are typically wider and carry
larger amounts of water.
Lakes and Ponds
littoral zone: The shallow zone of soil and water in
lakes and ponds where most algae and emergent
limnetic zone: A zone of
open water in lakes and
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.
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
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
coral bleaching: A phenomenon in which algae inside corals die, causing the corals to turn white.
Variations in climate determine the dominate plant growth
forms of terrestrial forms
biome: A geographic region categorized by a particular combination of average annual temperature,
annual precipitation, and distinctive plant growth forms on land, and a particular combination of
salinity, depth, and water flow in water.
tundra: A cold and treeless biome with low-growing vegetation.
permafrost: An impermeable, permanently frozen layer of soil.
small woody shrubs, mosses, heaths, and lichens, can
grow in shallow, waterlogged soil and can survive short
growing seasons and bitterly cold winters
boreal forest: A forest made up primarily of coniferous evergreen
trees that can tolerate cold winters and short growing seasons.
(sometimes called taiga) are forests made up primarily of coniferous (cone-bearing) evergreen trees
that can tolerate cold winters and short growing seasons
poorly suited for agriculture. However, these forests
serve as an important source of trees for pulp, paper,
and building materials. As a result, many have been
temperate rainforest: A coastal biome typified by moderate
temperatures and high precipitation.
combination of mild temperatures and high precipitation supports the growth of very large trees
temperate seasonal forest: A biome with warmer summers and
colder winters than temperate rainforests and dominated by
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.
hot deserts, includes the Mojave Desert, Sahara Desert, Arabian Desert, Great Victoria
Earth is characterized by patterns of temperature and precipitation. These patterns arise from the
circulation of air and ocean water, which is ultimately driven by unequal heating of Earth by the Sun,
the rotation of Earth, and Earth’s geographic features. Geographic variations in temperature and
precipitation have led to the development of distinct terrestrial biomes, which are defined by their
unique plant communities, and distinct aquatic biomes, which are defined by their particular