APES Unit 4 Earth's system and resources

Earth’s Atmosphere

The thin layer of gases surrounding Earth, Gravity holds these gases close to the surface.

How does Earth’s Atmosphere make life possible?

• Giving oxygen → Respiration

• Supplying carbon dioxide → Photosynthesis

• Protecting Earth from radiation

• Regulates Earth’s Temperature

Composition of Earth’s Atmosphere:

Nitrogen → 78%

Oxygen → 21%

Argon → 0.93%

Carbon dioxide → ~ 0.04%

Water Vapor → 0 - 4% (depending on location and water

Relationship: Air pressure and Altitude

Air pressure goes down as Altitude goes up

Air pressure goes down as Altitude goes up because…

• Gravity pulls air molecules towards the earth

• Most air molecules are concentrated in the lower atmosphere

• As you move higher, there are fewer air molecules to press you down

Layers of the Atmosphere:

• Exosphere

• Thermosphere

• Mesosphere

• Stratosphere

• Troposphere

Exosphere

• Exo = outside

• Gradually fades into space

Thermosphere

• Thermo = heat

• Auroras occur

• Temperature increases

Mesosphere

• Meso = middle

• Meteors burn up

• Temperature decreases

Stratosphere

• Strato = layer

• Contains the ozon layer

• Temperature increases

Troposphere

• Tropo = turning

• Weather occurs here

• Temperature decreases

The Greenhouse Effect steps

1. Solar radiation passes through the atmosphere

2. Earth’s surface absorbs the energy and warms

3. The warm surface releases heat radiation back

4. Greenhouse gases absorb and re-radiate some of this heat

5. Some heat escapes to space, while some is trapped near Earth’s surface

Without Greenhouse effect..

• Avg. Earth temp, would be about -18 C

• Actually avg. temp. is about 15 C

• Life as we know it would not exist

Why is Climate change bad?

Climate change makes this too much which is bad but greenhouse effect isn’t.

Major Greenhouse Gases:

• Water vapor → evaporation

• Carbon dioxide → fossil fuels combustion

• Methane → Livestock, landfills, natural gases

• Nitrous oxide → Fertilizers, agriculture

• Chlorofluorocarbon → Refrigerants and industrial chemicals (only one that’s caused just by humans)

The Enhanced Greenhouse Effect

• More greenhouse gases trap more heat in the atmosphere

• More CO2, less heat escapes to space, earth gets warmer

Solar Radiation

also known as Insolation means incoming solar radiation reaching earth

Solar energy drives:

• Weather

• Climate

• Winds

• Ocean currents

• The water cycle

• Photosynthesis

Sunlight angles

Earth is a sphere, so sunlight strikes different locations at different angles

The amount of heating depends on..

1. Surface Albedo

2. Sun Angle

3. Latitude

4. Day length

Albedo

How reflective something is

Low Albedo surfaces

• Forests, Oceans, Asphalt

• Absorbs more sunlight → becomes warmer

High Albedo Surfaces

• Snow, Ice, Clouds

• Reflect more sunlight → Remains cooler

Direct Sunlight

• High sun angle

  • Energy concentrated over smaller areas

  • More Intense heating

Indirect Sunlight

• Low sun angle

  • Energy spreads over a larger area

  • Less intense heating

What changes the sun angles?

Latitude

Sun angle: Poles

• Sunlight strikes at a lower angle

• Solar energy spreads over a larger area

• Lowest solar radiation

Sun Angle: Equator

• Sunlight strikes more directly

• Solar energy is concentrated

• Highest solar radiation

Relationship: Atmosphere and Solar energy

More Atmosphere = Less Solar Energy

Atmosphere vs Solar energy: Poles

• Sunlight travels through more atmosphere

• More Energy is lost before reaching Earth’s surface

Atmosphere vs. Solar Energy: Equator

• Sunlight travels through less atmosphere

• Less energy is scattered or absorbed

Earth’s rotation

Earth rotates on its axis once every 24 hours, causing day and night

Earth’s Tilt

• Earth’s axis is tilted 23.5 degree

• The axis always points in the same direction as Earth revolves

Earth’s title causes changes in day length throughout the year.

Tilted away → Shorter daylight

Tilted towards → Longer daylight

There is an unequal heating of Earth because…

• Polar regions receive much less solar radiation

• The equator receives the most direct solar radiation

• This uneven heating creates temperature difference across Earth

Which way does air move?

• Air naturally moves from high pressure to low pressure

• This horizontal movement of air is called wind

• Without pressure differences, wind would not exist

What creates warm and cold air?

1. Unequal heating creates warm and cold air, changing air density

2. Warm air rises cold air sinks

3. This creates pressure differences causing air to move from high pressure to low pressure (wind)

Convection

the transfer of heat through the physical movement of fluids, including liquids and gases

Atmospheric circulation steps:

1. Warm air rises near the equator

2. Air moves away from the equator

3. Cool air sinks near the poles

4. Surface winds return toward the equator

The three circulation cells are…

1. Hadley Cell

2. Ferrel Cell

3. Polar Cell

What do the circulation cells do?

These cells redistribute heat from the equator toward the poles

Hadley cell

1. Warm air rises near the equator.

2. Air cools, loses moisture, and sinks near 30° N/S.

3. Creates wet tropical regions and dry deserts.

Ferrel Cell

1. Surface air moves toward the poles and rises near 60° N/S.

2. Air cools and sinks near 30° N/S

3. Creates mid-latitude weather patterns.

Polar Cell

1. Cold, dense air sinks at the poles.

2. Surface air moves toward 60° N/S and rises.

3. Creates cold, dry polar climates.

Picture of the three circulation cells

Picture of the Global circulation patterns relating to the environmental condition

Jet streams

1. Fast-moving bands of air in the upper troposphere

2. Form near boundaries between circulation cells

3. Move weather systems around Earth

4. Influence climate and precipitation patterns

5. Examples:

   1. Polar Jet Stream (~60° N/S)

   2. Subtropical Jet Stream (~30° N/S)

How does wind move?

The Coriolis Effect

Moving air appears to curve, the apparent deflection of moving air caused by Earth’s rotation. It changes wind directions, not wind speed.

Wind deflection depends on hemisphere

Northern Hemisphere: Winds curve to the right

Southern Hemisphere: Winds curve to the left

The Coriolis Effect: Equator vs. Poles

The closer you are to the equator, the faster the Earth rotates because that region must travel a much larger distance in a 24 hour day than the area near the poles.

Type of Winds

1. Trade Winds

2. Westerlies

3. Polar Easterlies

Trade Winds

Move toward the equator

Westerlies

move toward the poles

Polar Easterlies

Move away from the poles

Earth’s Structure & Layers

Crust

• Thin, outermost solid layer of Earth where life exists

Lithosphere

• Rigid outer layer made of the crust and uppermost mantle

• Broken into large pieces called tectonic plates

Asthenosphere

• Hot, solid rock beneath the lithosphere

• Flows slowly over long periods of time, allowing tectonic plates to move

Mantle

• Thickest layer of Earth

• Made of hot, mostly solid rock that slowly circulates through convection currents, driving plate movement

Core

• Composed mainly of iron and nickel

• Extremely hot and provides the heat that drives convection within the mantle

Why isn’t the Earth’s surface fixed?

• The lithosphere is broken into moving tectonic plates

• Plate movement shapes Earth’s landscapes and creates natural hazards

Where do most of the earthquakes happen?

on the tectonic plate boundaries

What causes plates to move?

• Earth’s core provides heat

• Heat creates convection currents in the mantle

• Convection slowly moves tectonic plates

Picture of the convection Currents:

Types of Plate Boundaries

1. Divergent Plate Boundary

2. Convergent Plate Boundary

3. Transform Fault Plate Boundary

Divergent Plate Boundaries

• Plates move apart

• Constructive boundary

• New crust forms

Convergent Plate Boundaries

• Plate collide

• Destructive boundary

• Crust is recycled

Transform Fault Plate Boundaries

• Plates slide past

• Conservative boundary

• No crust formation or recycling

Continental Crust

• Made mainly of granite (less dense rock)

• Thicker

• Generally less dense

• Much older

• Form the continents

Oceanic Crust

• Made mainly of Basalt (denser rock)

• Thinner

• More dense

• Younger

• Form the ocean floor

Divergent Boundaries: Oceanic - Oceanic

• New oceanic crust forms

• Plates move apart

• Magma rises

• Seafloor spreading

• Mid - Ocean ridges

Divergent Boundaries: Continental - Continental

• Plates move apart

• Continental crust stretches and thins

• Magma rises through cracks

• Rift valleys form

• New Ocean basins may eventually form

Convergent Boundaries: Oceanic - Oceanic

• One oceanic plate subducts beneath the other

• Magma rises to form volcanic islands

• Forms:

  • Volcanic island arcs

  • Deep ocean trenches

  • Earthquakes

• Example: Japan or the Aleutian islands

Convergent Boundaries: Oceanic - Continental

• The denser oceanic plate subducts beneath the continental plate

• Partial melting produces magma that rises to the surface

• Forms:

  • Volcanoes

  • Coastal mountain ranges

  • Deep Ocean Trenches

  • Earthquakes

• Example: Andes Mountains

Convergent Boundaries: Continental - Continental

• Neither plate is dense enough to fully subduct

• The plates collide and buckle upward

• Forms:

  • Large mountain ranges

  • Strong earthquakes

  • Little to no volcanic activity

• Example: Himalayas

Transform Boundaries

• Plates slide past

• No crust created

• No crust destroyed

• Stress builds (potential energy stored)

• Earthquakes occur (kinetic energy released)

Where is each type of boundary? (picture)

Hot spots

• Areas where hot mantle material rises toward Earth’s surface

• Create volcanoes away from plate boundaries

• Moving tectonic plates over stationary hot spots form volcanic island chains

• Example: Hawaiian island

The Ocean and Atmosphere are connected

The ocean and atmosphere constantly exchange heat, moisture, and energy

• The surface waters of the ocean absorb solar energy

• Warm ocean water heats the air above it

• Warm water also increases evaporation, adding moisture to the atmosphere

• Warm, moist air becomes less dense and rises

• Rising air helps drive atmospheric circulation

Gyres

Large ocean cricles patterns due to global win

• (clockwise in N hem, counterclockwise in S hem.)

Normal Conditions in Tropical Pacific

Trade winds create an uneven distribution of ocean temperatures

• Trade winds push warm surface water from east to west

• Warm water accumulates near Indonesia and Australia

• The western Pacific becomes warmer than the Eastern Pacific

• The western Pacific becomes warmer than the eastern Pacific

• Cold, nutrient - rich water rises along the west coast of South America (upwelling)

Upwelling

Upwelling is when deep, cold ocean water rises to the surface, bringing the nutrients that supports marine ecosystems.

• often caused by surface winds pushing warm surface water away

Why is Upwelling important?

• Brings nutrients from deeper waters to the oceans surface

• Supports high biological productivity

• Creates some of the world’s most productive fishing regions

What is Walker Circulation?

The temperature difference across the pacific drives an east - west atmospheric circulation called walker circulation

Walker Circulation steps:

1. Warm ocean water heats the air above it

2. Warm, moist air rises over the western Pacific

3. Air moves eastward high in the atmosphere

4. Cooler, drier air sinks over the eastern Pacific

5. Surface trade winds complete the circulation

Hadley cells vs. Walker

Hadley cell: moves air north and south between the equator and 30 degree latitude

Walker: Moves air east and west alone the equator

El Nino: Walker Circulation weakens

• Trade winds weaken

• Warm surface water shifts eastward

• Upwelling decreases

• The eastern Pacific become warmer than normal

• Rising air and rainfall shift toward the central and eastern Pacific

Picture of the difference between Normal conditions and El Nino

La Nina: Walker Circulation Strengthens

• Trade winds strengthen

• More warm water is pushed westward

• Upwelling increases

• The eastern Pacific becomes cooler than normal

• Rising air and rainfall become even more concentrated over the western Pacific

Picture of the difference between Normal conditions and La Nina

Compare and Contrast El Nino and La Nina

Global weather patterns Change during El Nino and La Nina

Watershed

An area of land that channels rainfall, snowmelt and runoff downhill into a shared body of water like a stream, river, lake or ocean.

Rain shadow effect:

1. Wind pushed air up the mountain, causing it to cool

2. Cool air forms clouds and releases rain or snow on the windward side

3. After crossing the mountains the air descends and warms

4. The leeward side becomes dry because the air has lost most of its moisture

   1. This dry area is called a rain shadow

Climate patterns are affected by…

1. Latitude

2. Topography

3. Atmosphere

4. Ocean currents

5. Distance from Oceans

Latitude

Dictates solar intensity, direct sunlight makes the equator warm, while angles sunlight makes the poles cold

Topography

Higher elevations are colder, and mountain ranges create wet windward sides and dry leeward “rain shadows”

Atmospheric Circulations

Global winds move heat and moisture, creating rainy zones where air rises and dry deserts where air sinks

Ocean currents:

Warm currents bring heat and rain to coastal areas, while cold currents bring cooler, drier conditions

Distance from oceans

Water moderates temperature, keeping coastal regions mild while inland areas suffer extreme hot and cold seasons