Earth’s Major Spheres

Core Idea: We all are connected

  • Earth has four major spheres that constantly interact with each other

    • Hydrosphere-water

    • Lithosphere-land/rock

    • Atmosphere-air

    • Biosphere-all living things

  • Big Idea: Nothing on earth works in isolation, everything affects everything else

    • Concept of interconnectedness is central to Indigenous worldviews

    • Became mainstream with modern environmental movement in 1970

Earth’s four spheres

  • At any moment, matter exists in one of the four spheres

  • If one sphere is disturbed, the others are affected too

Hydrosphere

  • All forms of water on earth including

    • Oceans

    • Lakes

    • Rivers

    • Snow

    • Glaciers

    • Water underneath the surface

    • Water vapour in air

  • Cycles through ecosystems through 3 processes

    • Evaporation-water turns to vapour (heat)

    • Condensation-vapour turns to clouds

    • Precipitation-rain, snow falls back down

Geosphere

  • Contains all of the solid, rocky parts of the Earth

    • Planet’s surface (crust)

    • Semi solid land underneath crust (mantle)

    • Liquid land near the center of the planet (core)

Lithosphere/Major landforms

  • Contains the crust and uppermost part of the mantle

  • Includes various landforms like mountains, valleys, rocks, minerals, soil

  • Lithosphere is constantly being shaped by external forces such as the sun, wind, ice, water and chemical changes

Atmosphere

  • The gaseous part of Earth

  • Upper portion protects living things from the sun’s harmful UV radiation and absorbs and emits heat

  • Further away from the earth=lower air pressure

The Sun’s role in Earth Sphere

  • Solar energy is absorbed (taken in) and reflected (bounced back) by the atmosphere and surface

  • Heats earth’s surface unevenly

  • Global winds and ocean currents move heat around planet and redistribute heat

  • Solar energy enters the biosphere through photosynthesis and cellular respiration

  • At the equator sun rays hit directly-more heat concentrated

  • At the poles sun rays hit at an angle-heat spreads over a larger area-less warm

  • Because the earth is curved…

    • Strikes earth at different angles

      • Lower latitudes (near equator) receive more direct solar energy

      • Higher latitudes (near poles) receive less enrgy

Global winds system

  • How wind is created (convection currents)

    • Warm air near earth’s surface rises (warm air is lighter)

    • As it rises it cools down

    • Cool air is denser so it sinks back down

    • This sinking cool air creates wind that pushes warm air around

    • Coriolis effect- a change in the direction of moving air, water or other objects due to Earth’s rotation

  • When air temperature changes-weather occurs

  • Trade winds-near equator

  • Westerlies-mid latitudes

  • Polar easterlies-near the poles

Ocean currents

  • Move thermal energy around Earth

  • Surface currents are created by wind

  • Five major sets of surface currents (one in each ocean basin)