Global Climate and Biomes APES

Global Climates and Biomes

Unit 4

Global Processes Determine Weather and Climate 

Weather talks about the short-term conditions of the atmosphere in a local area. 

  • Temperature

  • Humidity

  • Clouds 

  • Precipitation

  • Wind speed 

  • Atmospheric pressure 

Climate talks about the average weather that occurs in a given region over a long period of time (several decades). 

Earth’s Atmosphere 

  1. Troposphere

    1. Atmospheric layer closest to Earth

    2. Temperature decreases with altitude 

      1. As you go up, temp gets lower

    3. Densest layer 

    4. Nitrogen, oxygen, and water vapor occur 

    5. Weather occurs 

  2. Peak ozone layer 

  3. Stratosphere

    1. Temperature increases with altitude 

    2. Sun’s rays warms the upper part 

    3. Less dense than the troposphere 

    4. Higher altitudes are warmer than the lower altitudes 

    5. Ozone 

      1. Absorbs most of the Sun’s UV rays 

  4. Mesosphere 

    1. Atmospheric density and pressure decreases as you go further into space 

  5. Thermosphere 

    1. Block harmful X-rays and UV radiation 

    2. Contains charged gas molecules when hit by solar energy they glow and produce light 

      1. Northern lights  

  6. Exosphere 

Unequal Heating of Earth 

  • Warming does not occur evenly across the planet because: 

    1. Variation in the angle at which the Sun’s rays strike Earth 

      • Sun’s rays travel a shorter distance to reach Earth’s surface in the tropics compared to the poles 

        • Striking Earth at a perpendicular angle vs. an oblique angle 

      • Solar energy is lost as it passes through the atmosphere → loses sunlight in high latitudes because it is being spread over a larger surface area 

    2. Variation in the amount of surface area over which the Sun’s rays are distributed 

      • Same explanation as angle; equator has more surface area compared to poles 

    3. Some areas of Earth reflect more solar energy than others 

      • The albedo of a surface is the percentage of the incoming solar energy that it reflects 

        • Higher albedo →more solar energy it reflects and less it absorbs

          • White surface has higher albedo than black surface 

          • Colder surfaces because of snow (which is white) reflects more sunlight and absorbs less of it 

Atmospheric Convection Currents

PROPERTIES OF AIR 

  • Air has 4 properties that determine how it circulates in the atmosphere 

    1. Density 

    2. Water vapor capacity 

    3. Adiabatic heating/cooling 

    4. Latent heat release

  • Density 

  • Determines movement 

  • Less dense air rises 

  • Denser air sinks 

  • Warm air has a lower density than cold air 

    • Warm air rises (this is why the basement is usually very cold and top of house is warmer) 

  • Water Vapor

    • When air cools and saturation point drops (because cool air sinks) the water vapor condenses into liquid water that forms clouds. 

    • Warm air has higher capacity for water vapor 

      • When it is hot it is also humid (warm air w/ water vapor) 

        • Saturation Point - maximum amount of water vapor that can be in the air at a given temperature 

  • Changes in pressure 

    • Air rises, pressure decreases

    • Lower pressure allows the rising air to expand in volume → lowers the temperature of the air 

      • Adiabatic cooling 

    • Air sinks towards Earth’s surface (so down) the pressure increases →air decreases in volume → raises temperature of air 

      • Think like a plane ascending the pressure on it increases 

      • Adiabatic heating 

  • Heat Release 

    • Latent heat release - when water vapor in the atmosphere condenses into liquid water, energy is released. This means that whenever water vapor in the atmosphere condenses, the air will become warmer and the warm air will rise. 

FORMATION OF CONVECTION CURRENTS 

  • Convection currents are global patterns of air movement that are initiated by the unequal heating of Earth. 

    1. Warming of Earth’s humid air at surface decreases density 

    2. Air begins to rise 

    3. Experiences lower atmospheric pressure 

    4. Adiabatic cooling 

    5. Reaches saturation point 

    6. Condensation → cloud formation 

      • Also causes latent heat release → makes air expand further and more rapidly 

  • Air rises continuously from Earth’s surface near the equator

    1. Air near top of troposphere → chilled by adiabatic cooling 

      • Contains little water vapor 

    2. Warm air rises from below, cold air is then displaced horizontally

    3. Displaced air sinks back to Earth’s surface 

      • Experienced higher atmospheric pressure bc of sinking air 

      • Causes adiabatic heating

    4. Air reaches Earth hot and dry 

      • This is why regions at 30 degree N and S are typically hot, dry deserts

  • Hadley cells - convection currents that cycle between the equator and 30 degrees N and S 

  • Desert air moves along Earth’s surface to complete the cycle 

  • The tropics experience seasonal patterns of precipitation because of the Earth’s tilt 

  • Polar cells - air that rises at 60 degrees N and S and sinks at the poles. 

    • Air cools at 60 and then turns into water vapor 

      • This is why when air rises precipitation happens

  • In all the three convection currents slowly move air of the tropics toward the mid-latitude and polar regions  

Earth’s Rotation and the Coriolis Effect 

  • The speed of Earth’s rotation varies with latitude

    • Faster travel on the equator 

  • Coriolis Effect - phenomenon that causes moving objects, like air and water, to appear to curve rather than move in straight lines when observed from a rotating frame of reference.  

    • The different rotation speeds of Earth at different latitudes cause a deflection in the paths of traveling objects 

    • Northern Hemisphere: Objects moving north or south are deflected to the right relative to their direction of travel. 

    • Southern Hemisphere: Objects moving north or south are deflected to the left relative to their direction of travel. 

  • Example - Image throwing a ball directly south from the North Pole to the equator. While the ball is in motion, the Earth rotates underneath it. 

    • By the time the ball reaches the equator, the surface there has moved faster to the east than where the ball started, causing the ball to land west of the intended target. 

    • This deflection happens because of the difference in rotational speeds between the starting and ending points.

  • Effect - Oceans currents, air masses, projectiles, migrating birds, planes are all affected by the coriolis effect 

  • Prevailing winds patterns produced by a combination of the Coriolis effect and convection currents 

    • Atmospheric Convection Currents - large scale movements of air caused by differences in temperature and pressure in Earth’s atmosphere 

      • Hadley cells 

        • Near the equator 

        • Warm air rises at the equator and moves towards higher latitudes then cools and sinks near 30 degrees 

      • Polar cells 

        • Near the poles 

        • Cold air sinks at the poles and moves toward the 60 degrees, where it rises again 

      • Ferrel cells 

        • In between 

        • Driven by the interaction of Hadley and Polar cells creating variable wind patterns 

    • Wind Patterns 

      • Trade Winds (0-30) 

        • Hadley cells 

        • Air sinks at 30 and moves towards equator 

        • Since earth’s surface rotates faster at the equator, it is deflected westward by the Coriolis effect 

      • Westerlies (30-60) 

        • Air moves away from the equator 

        • Air moves to the poles and is deflected eastward 

      • Polar easterlies (60-90) 

        • Air moves away from the poles 

        • Deflected westward 


Here’s a summary and explanation of the key ideas from your notes:

Seasons and Earth’s Tilt

  1. Earth’s Axis and Seasonal Changes:

    • Earth’s axis is tilted at 23.5°, causing different parts of the planet to receive varying amounts of sunlight throughout the year.

    • This tilt creates seasons, as the hemisphere tilted toward the Sun experiences longer days and warmer temperatures, while the opposite hemisphere experiences shorter days and cooler temperatures.

  2. Key Dates and Events:

    • Equinoxes:

      • March (20/21) and September (22/23).

      • The Sun shines directly over the equator, resulting in 12 hours of day and night globally.

    • Solstices:

      • June (20/21): The Sun is directly over the Tropic of Cancer (23.5° N), marking the longest day in the Northern Hemisphere.

      • December (21/22): The Sun is directly over the Tropic of Capricorn (23.5° S), marking the shortest day in the Northern Hemisphere.

Ocean Currents

Ocean currents significantly impact climate and ecosystems, driven by a mix of factors like temperature, gravity, wind, the Coriolis effect, and continental positions.

  1. Surface Currents (Gyres):

    • Gyres are large-scale circular currents.

    • They rotate clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere.

    • Surface currents redistribute heat:

      • Cold currents along west coasts (e.g., California Current) cool nearby land.

      • Warm currents along east coasts (e.g., Gulf Stream) warm nearby land.

  2. Upwelling:

    • Occurs when surface water diverges (moves apart), causing deep, nutrient-rich water to rise.

    • Supports productive ecosystems and commercial fisheries (e.g., off the coasts of California or Peru).

  3. Thermohaline Circulation:

    • Driven by differences in temperature and salinity.

    • Dense, salty water sinks in the North Atlantic, creating a global conveyor belt of deep ocean currents that circulate heat and nutrients worldwide.

    • This process takes hundreds of years to complete.

    • Climate Impact: If global warming reduces salinity (due to melting glaciers), thermohaline circulation could weaken, leading to cooler climates in places like Europe.

  4. Heat Transport:

    • Ocean currents moderate the climate of nearby land:

      • Gulf Stream brings warm tropical waters to Europe, keeping it warmer than similar latitudes like Newfoundland, Canada.

    • Changes in these currents due to global warming could disrupt this heat transport.

Key Connections:

  1. Seasons and Ocean Currents:

    • Earth’s tilt drives seasonal sunlight differences, while ocean currents redistribute heat, affecting global and regional climates.

  2. Ecosystems:

    • Upwelling zones fueled by currents support marine life by bringing nutrients to the surface.

  3. Global Warming Concerns:

    • Melting glaciers and reduced salinity may disrupt ocean circulation, potentially altering climates and ecosystems globally.

 

The rain shadow effect is a climatic phenomenon caused by mountains that influences local weather patterns and vegetation. Here's how it works, based on the PDF content:

  1. Moist Air from the Ocean:

    • Air moving inland from the ocean carries a significant amount of water vapor.

  2. Windward Side of the Mountain:

    • The air is forced to rise as it encounters a mountain range.

    • As the air rises, it undergoes adiabatic cooling (temperature drops as the air expands due to lower pressure).

    • The cooling causes water vapor to condense, forming clouds and resulting in precipitation on the windward side.

    • This side of the mountain typically experiences lush vegetation due to the high levels of rainfall.

  3. Leeward Side of the Mountain:

    • After releasing most of its moisture, the now-dry air descends on the other side of the mountain (the leeward side).

    • As the air descends, it undergoes adiabatic heating (temperature increases as the air compresses due to higher pressure).

    • This creates warm, dry conditions on the leeward side, often resulting in arid or desert-like landscapes.

  4. Resulting Climate Zones:

    • The windward side is characterized by a moist and green environment.

    • The leeward side is much drier and supports less vegetation, forming a rain shadow region.

Example from the PDF:

In North America, the Sierra Nevada range demonstrates this effect:

  • The western (windward) side receives heavy precipitation and supports lush forests.

  • The eastern (leeward) side, known as the Great Basin, is significantly drier and supports desert ecosystems.


Key Terms:

  • ENSO (El Niño-Southern Oscillation):

    • A recurring climate pattern involving changes in the temperature of waters in the central and eastern tropical Pacific Ocean.

    • Affects atmospheric pressure and ocean currents between South America and Australia/Southeast Asia.

Normal Year:

  • Trade winds blow from east to west.

  • Warm water accumulates near Australia and Southeast Asia.

  • Cold water upwells near the western coast of South America, supporting rich marine ecosystems.

El Niño Year:

  • Description:

    • Trade winds weaken or reverse.

    • Warm ocean water moves eastward toward South America.

    • Upwelling near South America is suppressed, reducing nutrient availability for marine life.

  • Effects:

    • Warmer winters in much of North America.

    • Increased precipitation and flooding on the west coast of the Americas.

    • Drier conditions leading to droughts in Southeast Asia and Australia.

    • Weakened monsoon activity in India and Southeast Asia.

    • Decreased hurricane activity in the Atlantic Ocean.

La Niña Year:

  • Description:

    • Trade winds strengthen.

    • Warm water is pushed further west, intensifying the upwelling of cold water near South America.

    • Cooler ocean temperatures dominate the central and eastern Pacific.

  • Effects:

    • Cooler, drier weather in the Americas.

    • Increased tornado and hurricane activity in the Atlantic Ocean.

    • Rainier and warmer conditions in Southeast Asia.

    • Enhanced monsoon activity in India and Southeast Asia.

Environmental Problems (FRQ Focus):

  • El Niño:

    • Flooding can damage infrastructure and displace populations.

    • Droughts in Australia and Southeast Asia lead to reduced crop yields and water scarcity.

  • La Niña:

    • Cooler, drier conditions in the Americas can harm agriculture.

    • Increased storm activity (hurricanes and tornadoes) poses risks to lives and property.

Summary Notes:

  1. ENSO Cycle:

    • Alternates between El Niño (warming) and La Niña (cooling).

    • Impacts global weather, agriculture, and ecosystems.

  2. Effects of El Niño:

    • Flooding in the Americas, droughts in Asia/Australia, reduced Atlantic hurricanes.

  3. Effects of La Niña:

    • Cooler, drier weather in the Americas, increased storms and monsoons in Asia.




Aquatic Biomes 


Factors that determine what organisms can survive in these environments

  • FW, SW, brackish 

    • If FW then is it standing or flowing

  • Wetlands -boundaries 

  • Depth of light penetration

  • Temperature 

  • Pressure 


Largest part of our biosphere are aquatic biomes 

  • More complex food webs compared to terrestrial biomes 

    • Different depths 

    • Photosynthesis confined to surface water 

    • A lot of it has not been studied yet 


  1. Marine Biomes 

    1. Oceans (open) - can be separated into three zones of light penetration 

      1. Photic

        1. Sharks and whales 

        2. Full light penetration

        3. High DO low CO2 

        4. Phytoplankton - important producers 

        5. Small nekton (swimmers) 

      2. Disphotic

        1. Smaller nekton 

        2. Decreases in temperature 

        3. Zooplankton 

        4. Rise to shallow water to feed every night  

      3. Aphotic

        1. No light penetration 

        2. Rely on marine snow 

          1. Organic debris 

        3. Organisms are adapted; bioluminese 

        4. High pressure 

        5. Low nutrients 

        6. Chemosynthesis 

    2. Coastal zones (intertidal zones) 

    3. Supplies most of the world’s oxygen through algae 

    4. Huge reservoirs for carbon 

      1. Via photosynthesis and gas diffusion

    5. 3.5 % salinity

      1. Seperated into: 

        1. Intertidal Zone 

          1. High tide and low tide 

          2. Alternating wet/dry 

          3. Coast of maine or down the shore 

        2. Neritic Zone 

          1. Over continental sheft 

          2. Coral reefs 

            1. Polyps that secrete calcium carbonate shells 

            2. Need clear warm water to survive 

          3. Kelp forests

            1. More temperate some polar regions 

            2. Rock with cold upwelling water 

        3. Open ocean 

  2. Freshwater Biomes 

    1. Streams, rivers, ponds, lakes (flowing water) 

    2. Less than 1% salinity organisms can’t survive higher salt concentrations than that 

      1. Standing water (lake or pond) broken up into 4 zone

        1. Littoral 

          1. Shallow area 

        2. Limnetic 

          1. Photic zone of open water 

          2. Photosynthesis 

          3. No rooted plants 

          4. Phytoplankton 

        3. Profundal 

          1. Aphotic zone 

          2. No light penetration 

        4. Benetic 

      2. Lakes - seasonal overturn 

        1. Wind helps micing of DO as it warms or cools t through 4 degrees C seasonally 

          1. Nutrient cycling 

  3. Wetlands 

    1. Boundary regions between terrestrial and aquatic biomes 

    2. Have to have organisms that can tolerate saturated soils 

      1. Soil is saturated to some type

    3. Can be categorized as marshes or swamps 

      1. Swamps - trees 

        1. Mangrove forests 

          1. Salt tolerant trees 

          2. Help stablize soil and sediments 

      2. Marshes - grasses

        1. Tidal marshes and tidal swamps 

        2. Nontidal marshes and nontidal swamps 

          1. Marshes - catails, floodplains

          2. Swamps - cypress trees or bottomland hardwood forest 


Intertidal zones (sandy) 

  • High and low tide occur 

Neptic zones 

Neutoric zones 

  • Coral 

  • Polyps 

Benthic zone - sea floor 

Seasonal overturn 

  • Mixture of DO

  • Winter body of water needs to heat to allow mixing of DO and inverse relationship in the summer 

Tidal wetlands - coastal regions 

Intidal wetlands - floodplains 


Marshes are one of the most productive biomes 

  • Mangrove forests 

Swamps and marshes are both salt tolerant