APES Chapter 6 Power Point.ppt

Chapter 6

Weather

• Weather is a local area’s short-term physical conditions Hours or days

• Troposphere

Variables of Weather

• Atmospheric pressure • Precipitation

• Temperature • Wind speed

Fronts: boundaries between 2 air masses with different temps and densities

Pressure systems

• High

Cool, dense air that descends toward earth’s surface, becomes warmer Fair weather

• Low

Less dense warm air that rises, expands and cools.

Tornadoes

• US most prone: March - Aug • Australia

Tropical Cyclone

• Atlantic – hurricanes • Pacific – Typhoons • Saffir-Simpson scale

• Immediate damage – loss of life and damage to property/agricultural production

• Long term damage in ecology/economy Erosion of physical features of land

Change population distribution of plants/animals Convey waterborne/airborne contaminants

Hurricanes are beneficial?

• Can flush excess nutrients from land runoff.

Hurricane Brett 1999 • Reduced brown tides

• Increased growth of sea grass/ served as nurseries for shrimp, crabs, fish

Factors Determining Climate

How is climate determined?

Global Air Circulation

a. Uneven heating: stronger at equator than poles (sun’s rays more at angle)

b. Seasonal changes in temp due to tilt of Earth c. Rotation in eastward direction prevents winds

from equator from moving N & S

Winds move to R in northern hemisphere, L in southern hemisphere. Coriolis Effect

• Polar Easterlies

d. Long-term variations in amount of solar energy striking the Earth

e. Properties of air and water

• Evaporation and heat transfer from oceans to atmosphere creates convection cells

that transport heat and water from one area to another.

Animation: Air Circulation and

Climate

PLAY ANIMATIO

Cell 3 North

Moist air rises — rain

Cell 2 North Cool, dry air falls

Cell 1 North

Moist air rises, cools, and releases Moisture as rain

Cell 1 South Cool, dry

air falls

Cell 2 South

Moist air rises — rain Cell 3 South

Cold, dry air falls Polar cap Temperate deciduous forest and grassland Desert Tropical deciduous forest Tropical rain forest Equator Tropical deciduous forest Cold, dry air falls Polar cap Arctic tundra Evergreen coniferous forest Temperate deciduous forest and grassland

2.

and cold ocean currents

a. Redistribute solar energy

Gyres

• Large ocean currents - North Atlantic Gyre

- Gulf Stream

Currents mix ocean waters and distribute nutrients and DO.

Upwellings

• Movement of nutrient rich bottom water to the ocean’s surface

Animation: Upwelling Along

Western Coasts

El Nino Southern Oscillation

ENSO

1. Prevailing westerlies weaken

2. Surface water along the South and North American (west) coasts becomes

warmer

3. Normal upwellings are suppressed

reduces primary productivity, causes sharp decline in pops of some fish

Animation: El Nino Southern

Oscillation

Typical Climate Changes with El Nino

• Torrential rains and mudslides along Ca coast. • Peruvian floods and mudslides

• Drought in Brazil, Indonesia, Australia, India, parts of Africa

La Nina

• Cooling episode that sometimes follows El Nino.

• More Atlantic Ocean Hurricanes

• Colder winters in Canada and Northeast • Warmer, drier winters in SE and SW US • Torrential rains in SE Asia

Chemical Makeup of Atmosphere and the Greenhouse Effect

• Certain gases play key role in determining temp and climate of Earth

• Greenhouse gases:

Water vapor, CO₂, CH₄ (methane), N₂O (nitrous oxide)

Greenhouse Effect

• Visible light, IR, UV pass through troposphere • Earth’s surface absorbs much energy and

transforms to IR (2nd law of thermodynamics)

which rises back into troposphere.

• Some heat escapes to space, some is absorbed by greenhouse gases and emitted into

troposphere as longer IR rays which warms the atmosphere

Greenhouse Effect & Global

Warming

• Human activities increase greenhouse gases

 increased greenhouse effect.

• May lead to global warming causing 1. Altered precip patterns

2. Altered areas for crop growth

3. Rise in sea level – thermal expansion and melting ice caps

Anthropogenic Activities Leading to

Increased Greenhouse Gases

• Increase in CO₂ emissions – burning of fossil fuels

Animation: Increasing

Greenhouse Gases

Animation: Greenhouse Effect

Chemical Makeup of Atmosphere

• 3O₂ + UV  2O₃

• Stratospheric Ozone prevents 95% of UV rays from reaching Earth

• Prevents tropospheric gases from entering stratosphere

• Acts as thermal cap to determine average temp of troposphere

Topography/Earth Surface Features Effect on Climate

• Topographic features can produce microclimates • Mountains can interrupt flow of winds and

movement of storms. windward slope

leeward slope

Fig. 5-8, p. 105

Prevailing winds pick up moisture from an ocean.

Dry habitats Moist

habitats

On the leeward side of the mountain range, air descends, warms, and Releases little moisture. On the windward

side of a mountain range, air rises, cools, and

Microclimates in Cities

• Pavement, building materials absorb and hold heat

• Buildings block wind flow

• Motor vehicle emissions release heat & pollutants

Land/Ocean Breeze Interactions

Animation: Coastal Breezes

BIOMES:

CLIMATE AND LIFE ON LAND

• Different climates lead to different

communities of organisms, especially vegetation.

– Biomes – large terrestrial regions characterized by similar climate, soil, plants, and animals.

– Each biome contains many ecosystems whose communities have adapted to differences in

Fig. 5-9, p. 106 Polar ice Equator Tropic of Capricorn Tropic of Cancer High mountains

Polar grassland (arctic tundra) Temperate grassland Tropical grassland (savanna) Chaparral Coniferous forest

Temperate deciduous forest Tropical forest

BIOMES:

CLIMATE AND LIFE ON LAND

• Biome type is determined by precipitation, temperature and soil type

Figure 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 6-22

Plant Survival Strategies

• Desert – succulent plants, no leaves (no water loss), store water in fleshy tissue, open stomata for CO₂ only at night

• Tropical rainforest – broadleaf evergreens allow for collection of sunlight and radiation of heat

• Cold/dry winters – broadleaf deciduous survive drought and cold by shedding leaves and

becoming dormant