APES 4.5-5.5

Why do convection cells matter?

They distribute heat and influence global climate

Weather

Short-term atmospheric conditions at a specific time and place

Oceanic Conveyor Belt

Global warming might turn it off which would cause catastrophic damage because it distributes heat and regulates climate

Warm front's role in cloud formation

When a warm parcel of air (a warm front) moves to meet a cold parcel of air and pushes over the cold air, moving upwards to form clouds.

What are air fronts?

Boundaries where two air masses with different temperatures and densities meet. Fronts cause weather changes like clouds, wind, and precipitation.

Climate

Long-term average weather patterns over about 30 years, repeating

What is the difference between weather and climate?

Weather is short-term conditions; climate is long-term patterns

Why doesn't a cold weekend disprove global warming?

Climate trends are measured globally over long periods, not short-term local weather

Global warming

The long-term increase in global average temperature compared to preindustrial levels that leads to climate change

How do clouds form (physics explanation)?

Warm air rises, expands, and cools until water vapor condenses into droplets or ice crystals. Also when a cold parcel of air (a cold front) moves to meet a warm parcel of air, the cold air pushes the warm air upwards, forming clouds.

Adiabatic cooling

Cooling of rising air due to expansion at lower pressure

Troposphere

Closest atmospheric layer to Earth where weather occurs

Stratosphere

Layer containing the ozone layer that absorbs UV radiation

Mesosphere

Coldest atmospheric layer where meteors burn up

Thermosphere

Layer with very high temperatures, auroras, and the ionosphere

Exosphere

Outermost atmospheric layer that merges with space

Why do scientists divide the atmosphere into layers?

Based on changes in temperature with altitude

In which layer does weather occur?

Troposphere

In which layer is the ozone found?

Stratosphere

Convection cells

Circulation patterns formed when warm air rises and cool air sinks

Prevailing winds

Global wind patterns created by convection cells and Earth's rotation

What factors influence regional climate?

Latitude, elevation, proximity to water, ocean currents, winds, and topography

Why do we have seasons?

Earth's axial tilt causes changes in sunlight angle as it revolves around the Sun

What increases seasonal variation?

Greater distance from the equator and oceans

What decreases seasonal variation?

Proximity to oceans and equator

When is Earth closest to the sun in the Northern Hemisphere?

Winter

Why is winter colder even though Earth is closer to the sun?

Sunlight is less direct and days are shorter

Rain shadow effect

Dry conditions on the leeward side of mountains due to blocked precipitation

How does a rain shadow form?

Air rises, cools, drops moisture, then descends dry

Where do rain shadows occur?

Happens in Nevada, the Sahara, and the Mojave Desert

Upwelling

Cold, nutrient-rich deep water rising to the surface

What causes upwelling?

Wind movement and the Coriolis effect

Why is upwelling important?

It increases nutrients and supports marine life

Gyres

Large circular ocean current systems

What powers ocean gyres?

Wind patterns and the Coriolis effect

How do gyres affect climate?

They redistribute heat around the planet

Coriolis force

Apparent deflection of moving air and water due to Earth's rotation

Coriolis effect in the Northern Hemisphere

Deflects movement to the right

Coriolis effect in the Southern Hemisphere

Deflects movement to the left

What global patterns does the Coriolis force create?

Prevailing winds and ocean gyres

Oceanic conveyor belt

Global circulation moving warm and cold water

Why might the ocean conveyor belt stop?

Freshwater input reduces salinity and density

What would happen if it stopped?

Major global climate disruptions

El Niño

Warm ENSO phase with reversed winds and currents

How often does El Niño occur?

Every 4-6 years

El Niño effect on California

Wetter and rainier conditions

Global impact of El Niño

Warmer atmosphere

Dangers of strong El Niño events

Heat waves, droughts, flooding, disease, famine

La Niña

Cool ENSO phase

La Niña effect on California

Drier conditions

Global impact of La Niña

Cooler atmosphere

Tragedy of the commons

Overuse of shared resources due to individual self-interest

Example of tragedy of the commons

Overfishing in international waters

Watershed (drainage basin)

Land area that drains into a common water body

Why are watersheds important?

Actions upstream affect downstream ecosystems

Downstream pollution

Pollutants accumulate farther downstream

Sedimentation

Soil runoff increases turbidity

Thermal pollution

Changes water temperature and flow

Pesticides

Chemicals designed to kill pests

Insecticides

Kill insects

Fungicides

Kill fungi

Herbicides

Kill weeds (e.g., glyphosate)

Fertilizers

Substances that promote plant growth

NPK

Nitrogen, phosphorus, potassium

Synthetic fertilizer

Fast-acting nutrients

Organic fertilizer

Slow-release nutrients

Nitrogen forms plants use

NH₃/NH₄⁺, NO₂⁻, NO₃⁻, urea

Phosphorus form

PO₄³⁻

Potassium form

K⁺

Industrial agriculture

High-yield monoculture using chemicals

Subsistence farming

Small-scale farming for personal use

Slash

and-burn agriculture - Burning vegetation to temporarily enrich soil

Sustainable farming

Crop rotation, polyculture, reduced inputs

Agricultural Revolution

Shift from hunting-gathering to farming ~10,000 years ago

Impact of the Agricultural Revolution

Increased food production and population growth

Environmental downside of early agriculture

Soil depletion

Industrial Revolution

Mechanization and technological innovation

Industrial Revolution food impact

Increased food production and distribution

Industrial Revolution population impact

Rapid population growth and urbanization

Green Revolution

Development of high-yield crop varieties

Who benefited from the Green Revolution?

Developing countries in Asia and Latin America

Negative impacts of the Green Revolution

Chemical dependence, biodiversity loss, water damage

Agriculture impact on aquifers

Depletion

Runoff from agriculture

Erosion and sedimentation

Sediment effect

Increased turbidity

Pesticide runoff

Kills organisms

Fertilizer runoff

Causes algal blooms

Clear

cutting - Removal of all trees in an area

Environmental impact of clear

cutting - Habitat loss and erosion

Selective cutting

Removal of specific trees

Why is selective cutting more sustainable?

Preserves ecosystem structure

Sustainable forestry

Reforestation and reduced-impact logging

Drip irrigation

Delivers water directly to plant roots

Furrow irrigation

Water flows through channels between rows

Spray irrigation

Mimics rainfall

Spray irrigation drawback

Evaporation and wind loss

Flood irrigation

Entire field flooded

Flood irrigation drawback

Salinization and evaporation

Contour tillage

Plowing perpendicular to slope

Terracing

Creating steps on hillsides