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FRONTS the movement of warm and cold masses of air creates the weather, and when the two clash, it often rains. A warm front is defined as the transition zone where a warm air mass is replacing a cold air mass. Warm fronts generally move from southwest to northeast and the air behind a warm front is warmer and more moist than the air ahead of it. When a warm front passes through, the air becomes noticeably warmer and more humid than it was before.humid
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Chapter 5
Climate and Terrestrial Biodiversity
CLIMATE: A BRIEF INTRODUCTION
• Weather • Climate - Latitude and elevation help
determine climate.• Warm front• Cold front• High pressure• Low pressure• Adiabatic cooling
FRONTS the movement of warm and cold masses of air creates
the weather, and when the two clash, it often rains. A warm front is defined as the transition zone where a
warm air mass is replacing a cold air mass. Warm fronts generally move from southwest to northeast and the air behind a warm front is warmer and more moist than the air ahead of it. When a warm front passes through, the air becomes noticeably warmer and more humid than it was before.
FRONTS
• A cold front is defined as the transition zone where a cold air mass is replacing a warmer air mass. Cold fronts generally move from northwest to southeast. The air behind a cold front is noticeably colder and drier than the air ahead of it. When a cold front passes through, temperatures can drop more than 15 degrees within the first hour.
FRONTS
PRESSURE SYSTEMS• The air associated with a high pressure system sinks
down from above and warms as it does so and is very stable.
• A high pressure system (anticyclone), is a system of closed isobars surrounding a region of relatively high pressure. When compared with low pressure systems, highs tend to cover a greater area, move more slowly and have a longer life.
• When the high pressure system is located over land the weather will be typically dry and free of cloud.
PRESSURE SYSTEMS
• A low pressure system (cyclone) develops where relatively warm air ascends from the Earth's surface. These are systems of closed isobars surrounding a region of relatively low pressure.
• As the rising air cools, clouds will begin to form. The instability of the air will produce quite large vertical development of cumuliform clouds with associated rain showers (such as cumulonimbus cloud).
Adiabatic Cooling
• Adiabatic cooling deals with the cooling of parcels of air as they rise, or are forced up, through the atmosphere.
Adiabatic cooling
Adiabatic cooling
Adiabatic cooling
Earth’s Current Climate Zones
Figure 5-2Figure 5-2
Solar Energy and Global Air Circulation: Distributing Heat
Climate is affected by:• 1) Uneven heating of
the earth’s surface• 2) Seasonal changes
in temperature and precipitation
• 3) Earth’s rotation• 4) Unique properties
of air & water
Figure 5-3Figure 5-3Diagram
Coriolis Effect• Deflection of air
due to the rotation of the earth & friction between air & Earth – less effect near the equator (fewer hurricanes within 5 degrees)
Figure 5-4Figure 5-4
Coriolis Effect
Trade Winds
Convection Currents
• Drive day-to-day weather patterns
• Rain-shadow Effect
Figure 5-5Figure 5-5
Convection Cells• Distribute heat &
moisture• 6 Vertical currents at
different latitudes : • Hadley Cell – 0 – 30
- tradewinds• Ferrel Cell – 30-60-
westerlies• Polar Cell- 60 – 90 -
easterliesFigure 5-6Figure 5-6
El Nino/ENSO• Equatorial winds weaken along
Eastern Pacific• Surface water warms• No upwelling• Increased flooding in e. Pacific• Drier western Pacific• Fewer Atlantic hurricanes
World Map
La Nina
• Exaggerated normal pattern• Cooler water than normal
along eastern Pacific• Drier eastern Pacific• Flooding along western
Pacific• More Atlantic hurricanes
Topography and Local Climate:Land Matters
• Rain Shadow effect• Microclimates (forests, cities)• Sea breezes• Land breezes
Figure 5-8Figure 5-8
BIOMES: CLIMATE AND LIFE ON LAND
• Biomes – large terrestrial regions characterized by similar climate, soil, plants, and animals.
• Latitude vs. altitude• Succulents• Evergreens• Deciduous plants• Coniferous plants
BIOMES: CLIMATE AND LIFE ON LAND
Figure 5-9Figure 5-9
BIOMES: CLIMATE AND LIFE ON LAND
• Biome type is determined by precipitation, temperature and soil type
Figure 5-10Figure 5-10
BIOMES: CLIMATE AND LIFE ON LAND
• Parallel changes occur in vegetation type occur when we travel from the equator to the poles or from lowlands to mountaintops.
Figure 5-11Figure 5-11
DESERT BIOMES
• 30% of Earth’s land• Evaporation exceeds precipitation.• Little vegetation.
– Found in tropical (Sahara), temperate (Mojave) and cold regions (Gobi).
• Succulent plants• Deep vs. widespread roots• Some plants secrete toxins into soil
(sagebrush)• Small animals
DESERT BIOMES
• Tropical, temperate and cold deserts.
Figure 5-12Figure 5-12
GRASSLANDS AND CHAPARRAL BIOMES
• Tropical grasslands (savannas)• Temperate grasslands (prairies)• Chaparral (Mediterranean, SoCal) • Wet/dry season• Many are fire-maintained (many plants
contain oils)
GRASSLANDS AND CHAPARRAL BIOMES
• Most grasslands have alkaline soil
• Temperate grasslands are nutrient-rich
Figure 5-14Figure 5-14
Polar Grasslands
• Tundra - covered with ice and snow except during a brief summer (permafrost)
• Seasonal wetlands • Lots of migratory
animals & mosquitoes
Figure 5-17Figure 5-17
Chaparral
• Moderate climate
• Dense thickets of spiny shrubs
• Subject to periodic fires
Figure 5-18Figure 5-18
FOREST BIOMES• Tropical rainforest• Tropical deciduous
forest• Temperate
deciduous forest• Temperate rain
forest• Coniferous forest
(boreal, taiga).Figure 5-19Figure 5-19
Tropical Rain Forest• Heavy rainfall • High biodiversity• Broadleaf
evergreens• Nutrient-poor soil• High decomposition
rate
Figure 5-20Figure 5-20
Temperate Deciduous Forest• Most of the trees
survive winter by dropping their leaves, which decay and produce a nutrient-rich soil
• Moderate rainfall
Figure 5-22Figure 5-22
Evergreen Coniferous Forests• Mostly cone-
bearing evergreen trees - keep their needles year-round
• Insulating factor - helps the trees survive long and cold winters
• Sheds snow
Figure 5-23Figure 5-23
Temperate Rain Forests
• Coastal areas (Calif., Oregon, Washington) - huge cone-bearing evergreen trees such as redwoods and Douglas fir
• Cool moist environmentFigure 5-24Figure 5-24
MOUNTAIN BIOMES• High-elevation
islands of biodiversity
• Snow-covered peaks - reflect solar radiation
• Release water to lower-elevation streams and ecosystems.
Figure 5-25Figure 5-25
Fig. 5-26, p. 123
Natural Capital Degradation
Desert
Large desert cities
Soil destruction by off-road vehicles
Soil salinization from irrigation
Depletion of groundwater
Land disturbance and pollution from mineral extraction
Fig. 5-27, p. 123
Oil production and off-road vehicles in arctic tundra
Overgrazing by livestock
Release of CO2 to atmosphere from grassland burning
Conversion to cropland
Grasslands
Natural Capital Degradation
Fig. 5-28, p. 124
Clearing for agriculture, livestock grazing, timber, and urban development
Conversion of diverse forests to tree plantations
Damage from off-road vehicles
Natural Capital Degradation
Forests
Pollution of forest streams
Fig. 5-29, p. 124
Natural Capital Degradation
Mountains
Agriculture
Timber extraction
Mineral extraction
Hydroelectric dams and reservoirsIncreasing tourism
Urban air pollution
Increased ultraviolet radiationfrom ozone depletion
Soil damage from off-roadvehicles