Ch. 7 Climate and Terrestrial Biodiversity

Weather

set of physical conditions of the lower atmosphere in an area over a period of hours to days

Front

boundary between two air masses with different temperatures and densities

Warm front

advancing warm air mass is less dense and rises up over cooler air; moisture begins to condense and form layers of clouds at different altitudes

Cold front

advancing cold air mass (dense) stays close to the ground, wedging below warmer air; produces thunderheads

Atmospheric pressure

greater near the earth’s surface, due to weight of overlying atmospheric gas

High-pressure air mass

• Contains cool, dense air

• Descends slowly

• Lack of condensation leads to dry weather

Low-pressure air mass

• Contains low-density, warm air

• Air rises, expands, and cools

• Moisture condenses when temperature drops below dew point, around condensation nuclei

• Condensation may lead to precipitation

Climate

average weather conditions in at least 3 decades to thousands of years (e.g. tropical, polar, temperate)

Key factors that determine area’s climate

• Incoming solar energy

• The earth’s rotation

• Global patterns of air and water movement

• Atmospheric gases

• The earth’s surface features

Factors that determine regional climates

• Cyclical movement of air driven by solar energy and convection 

  • Heavier air masses sink replacing hotter and less dense air masses, forming convection cells

• Uneven heating of earth’s surface by sun

• Tilt of earth’s axis and resulting in seasonal changes

• Rotation of earth on its axis; trade winds

• Ocean currents that redistribute heat from the sun

Trade winds

reliable direction of winds due to Earth’s rotation

Atmospheric gases

nitrogen and oxygen

4 main greenhouse gases

• Water vapor (H2O)

• Carbon dioxide (CO2)

• Methane (CH4)

• Nitrous oxide (N2O)

Natural greenhouse effect

Earth’s surface absorbs solar energy and re-emits it as heat, gases keep the earth habitable by trapping that head which enhancing global warming

Rain shadow effect

most precipitation falls on windward side of mountain ranges; thus causing deserts as the air that descends is warm and releases little moisture

Desert biome

Biome with low and scattered annual precipitation

Desert plant survival adaptations:

• Shed leaves during hot/dry spells

  • Leaves exchange moisture and gasses from atmosphere, losing water

• No leaves that can lose water

• Store water and synthesize food in flesh stems

  • Cacti

• Deep roots tap into groundwater

• Wax-coated leaves that reduce water loss

• Seeds remain inactive until water available

Desert animal survival adaptations

• Hiding in cool burrows

  • Nocturnal 

• Camels drink water and store

• Thick, scaly coverings minimize water loss

Grassland biome

areas too moist for deserts but too dry for forests; maintained by combination of seasonal drought, grazing, and fires

Savanna

tropical grasslands that are hot throughout the year but normally wet and dry seasons exist

Temperate grasslands

areas used as prime target for agricultural activities but temperature falls below freezing during winter

Arctic tundra

area with very slow growth during short summers

Permafrost

soil that is permanently frozen

Forest biome

lands filled with biodiversity, dominated by trees

Tropical rainforests

hot areas with high moisture that host 50% of terrestrial organism species

Temperate deciduous forest

forests with cooler temperatures with abundant moisture

Cold coniferous forest(taigas)

forests characterized by cold winters and short summers with a short growth season and slow growing trees

Mountains

steep or high-elevation lands that occupy a large portion of the world’s forests with a huge percentage of biodiversity

Human Effects on Deserts

• Large desert cities

• Destruction of soil by off-road vehicles

• Depletion of ground

Human Effects on Grasslands

• Conversion to cropland

• Release of CO2 to atmosphere from burning grassland

• Overgrazing by livestock

• Oil production of off-road vehicles

Human Effects on Forests

• Clearing for agriculture, livestock grazing, timber, and urban development

• Conversion of forest to plantations

• Damage from off-road vehicles

• Pollution of forest streams

Human Effects on Mountains

• Agriculture

• Timber and mineral extractions

• Hydroelectric dams and reservoirs

• Air pollution from urban areas and power plants

• Soil damage from off-road vehicles