Earth’s Spheres 10.1
The Earth System is all of the matter, energy, and processes within Earth’s boundaries.
- The geosphere = the mostly solid, rocky part of Earth (crust, mantle, core).
- The hydrosphere = the part of Earth that is liquid water (salt water 97%, fresh water 3%)
- The cryosphere = all of the frozen water on Earth (glaciers, icebergs, snow, ice shelves)
- The atmosphere = the mixture of gases that surrounds Earth (nitrogen, oxygen, CO2, argon)
- The biosphere = all the living things and the areas of Earth where they are found
(organisms are in soil, water, on the surface, and in the lower atmosphere)
All these spheres interact by exchanging matter and energy. (For example: organisms of the biosphere
breathe air from the atmosphere, live on the geosphere, and drink water from the hydrosphere).
The Atmosphere 10.2
The atmosphere is made of nitrogen, oxygen, and other gases. It is divided into 4 distinct layers based
on their temperature differences.
- The troposphere has 80% of the total mass, and our weather.
- The stratosphere has the ozone layer.
- The mesosphere in which meteoroids burn up.
- The thermosphere which has very hot, but very few air molecules.
The ozone layer protects us from harmful solar radiation. Too much ultraviolet radiation can lead to
sunburn, eye damage, and skin cancer.
Energy Transfer 10.3
Energy, in the form of heat, can be transferred in Earth’s system in 3 ways:
- Radiation is the transfer of energy as electromagnetic waves (the sun’s rays, light bulbs, fire)
- Convection is the transfer of energy through the movement of matter (Convection currents are
caused by warm, less dense material rising while cold, dense material is sinking. This can be
found in the atmosphere, the oceans, and in the mantle.)
- Conduction is the transfer of energy through direct contact (hot sand touches the air directly
above it)
Heat always transfers from the hotter object to the cooler object.
Specific heat is the difference in how fast or slow an object heats up and cools down.
Wind in the Atmosphere 10.4
There are 2 types of wind; Global winds and Local winds.
Wind is caused by uneven heating of Earth’s surface and by the rotation of Earth on its axis (also called
the Coriolis effect).
The Coriolis effect is responsible for the global winds.
- The Polar Easterlies are at the poles, and blow from east to west.
- The Westerlies are at the mid-latitudes, and blow from west to east.
- The Trade Winds are by on either side of the equator, and blow from east to west.
(Winds are usually named based on the direction FROM which they are blowing.)
Uneven heating of the Earth’s surface is responsible for the local winds.
- A Sea Breeze blows from the water to the land during the DAY.
- A Land Breeze blows from the land to the water during at NIGHT.
- A Valley Breeze blows from the valley up the mountain side during the DAY.
- A Mountain Breeze blows from the mountain side down to the valley at NIGHT.
Remember, warm air is less dense and rises out of the way, then cooler, denser air rushes in to take its
place. That’s wind!
Ocean Currents 10.5
Ocean currents are the streamlike movements of water.
There are 3 types of currents:
- Surface currents are caused by global wind, the Coriolis effect, and continental deflections.
- Deep currents are caused by differences in water density (due to temperature and salinity).
- Convection currents are when surface currents and deep currents link together. Again, this is
caused by differences in density (warm water is less dense than cold water and very salty water
is more dense than less salty water).
Upwelling is when winds cause warm surface water to move away from the shore, and it gets replaced
with cold, nutrient-rich water from the deep ocean. This process brings in the tiny organisms that act as
food to the larger fish, thus creating a healthy, rich environment for fisheries.