Earth is sometimes called the water planet because 71% of its surface is water. Earth has the most water of any planet in the solar system!
Two influences on the many variations in Earth’s water supply: Natural occurrences & Human activities
Humans do not drink salt water. Humans drink fresh water that is potable
THE DISTRIBUTION OF WATER ON EARTH
Earth's water cycle is very important because it controls the distribution of water on Earth
Earth’s water exists naturally in different forms:
Solid (ice)
Liquid
Gas (vapour)
WATER ON EARTH
Freshwater only makes up 3% of all the water on Earth Of that freshwater only 1% is available for human consumption That means only 0.03% of all the water on Earth is available for humans to drink (Also known as Potable Water). That is a tiny amount! Why such a small amount of fresh water?
Fresh water trickles too far below the Earth’s surface to retrieve it
Fresh water is located too far from human habitats (ex. we don’t live close enough to it)
The rest is salt water which we can not drink
WATER AROUND THE GLOBE
Q: How many oceans are there? A: Technically one! The ‘oceans’ are all connected, but we divide them further into the following:
Pacific Ocean
Atlantic Ocean
Indian Ocean
Antarctic Ocean / Southern Ocean
Seas are smaller and not as vast as oceans, they are also not as deep as oceans. (think of seas as mini-oceans) Ocean and seas are considered saltwater systems!
WHY ARE OCEANS SO SALTY?
Oceans and seas are fed by river water, and rain water. When river water flows it picks up small deposits of minerals, these minerals along with the river water are eventually washed out to sea/ocean. Q: How come river water is not salty? But it makes the ocean salty? A: Over millions of years the rivers have been depositing small amounts of mineral salts into the ocean. Over time that small amount collects and increases the salt concentration of the oceans.
MOVEMENT OF WATER IN THE OCEANS
Q: Why is Great Britain warmer than Edmonton? A: The global conveyor belt of heat transports warm water to the coasts near Great Britian
CURRENTS:A stream of water that moves within a larger body of water. Carries warmer & colder water to different areas Surface water currents mainly caused by:
wind
tides
Earth’s rotation
Ex. Waves, and rip currents
Deep water currents mainly caused by
temperature differences in the water
salinity differences in the water
Earth’s rotation
Ex. Gulf Stream
CURRENTS AFFECT TEMPERATURE & CLIMATE
OCEAN CURRENTS AND TEMPERATURESurface currents are caused by steady winds, this moves the water great distances.
For instance warm water from the Gulf of Mexico moves all the way to the North Atlantic which warms Europe’s climate
Warm or cold currents greatly influence the climates on land.
OCEAN CURRENTS AND PRECIPITATIONThe temperature of an ocean current affects more than just air temperature; it also affects the amount of precipitation in an area. Warm air holds more moisture than cold air.
Winds over a warm current (ex. Scotland)– warm air carries lots of water - expect rain.
Winds over a cold current (ex. Labrodor)– cold air carries little water - expect no rain.
Currents are different from waves because the water moves from place to place.
WAVES
WAVES:Up and down movements on the surface of all bodies of water, even small puddles, have waves! Waves do not move water, energy is just transferred through the water as a wave. (Think of it like tying a rope to a door knob and shaking it, the rope moves up and down, but it actually doesn’t move from left to right)
Strong storms cause high winds that blows across water
Small waves are created, and combine, creating larger waves
Large waves combine to form a swell
Swells produced out at sea eventually travel to the shoreline and ‘breaks’ on the shore
Swells in open water appear to move up and down. FACTORS AFFECTING SWELLS:
Large wind speeds
Distance the wind blows over the water (called fetch)
Time wind has blown over fetch
EFFECTS OF WAVES ON SHORELINES
The force of waves can affect both a hard rock and soft sand shoreline.
Breaking waves regularly impact shorelines causing erosion of land surfaces.
TIDES
TIDES:Daily changes in water level of the oceans. Tidal changes are seen regularly along the coast. There are 2 high tides and 2 low tides a day:
High Tide – highest water level along the coast
Low Tide – lowest water level along the coast
TIDES FORCE ARE CAUSED BY:
The moon’s gravitational force is the primary cause of tides
Centripetal force causes water to bulge more at the equator
The sun also has an influence, but it is very small
HOW DOES THE MOON CREATE TIDES?
The side closest to the moon feels a strong pull from the moon creating a bulge.
The opposite side of the Earth also has a smaller bulge due to the moon pulling on Earth
The two bulges on both sides of Earth are the high tides.
People keep track of the tides with guides called tide tables. Q: What is a Rip Tide? A: When the tide is receding (high tide to low tide) through an estuary it can pull a large amount of water through a narrow gap, this can pull objects off into sea very quickly.
OCEANIC BASINS
PROCESSES THAT FORM OCEAN BASINS
The Earth is very old, and much of what we know has changed - It's 4.5 - 4.6 billion years old! (Life started 3.7 billion years ago)
The Lithosphere is the solid outer part of Earth, made of rock, which has broken into tectonic plates that are moving constantly and slowly due to convection currents within Earth’s molten core.
If we stripped the Earth of water we would see the solid outer surface of Earth (lithosphere). This outer part has high points (mountain ranges) and low points (basins).
If we were to re-introduce the water back into Earth it would to trickle down to the lowest points of the lithosphere hence filling and forming oceanic basins.
Think - oceans are the world’s sinks because of their low elevation
EXAMPLES HOW WATER CAN EFFECT THE CLIMATE
CLIMATE:Average weather measured over a long period of time.
THE EFFECT OF LARGE BODIES OF WATER ON CLIMATE Water has a high heat capacity, it can hold heat longer than other substances, this prevents wild temperature swings!
Cities next to large lakes are cooler during summer, and warmer in the fall (Chicago)
Ex. Hawaii’s temperature stays relatively close to an average temp, the water of the Pacific ocean prevents it from getting very cold or very hot
THE SNOW LAKE EFFECT: Large bodies of water influence the weather and climate in their regions as well
Geography affects precipitation as well, mountains and elevations cause water in moist to be deposited.
CHINOOK WINDS: Chinooks are abnormally warm winds that sweep across the prairies. They are created by a rain shadow effect from the Rocky Mountains.
RAIN SHADOW EFFECT
Warm moist air from the ocean moves over land
As it moves over the land it deposits most of the moisture (especially at high elevations)
What’s left is a warm dry air with very little moisture
In Alberta, the Rocky Mountains create a rain shadow, moist clouds move over British Columbia and deposit rain, once the warm air reaches the mountains it deposits what ever moisture it has left. The warm dry air continues over the mountains. In Alberta — Calgary resides in this “rain shadow”, during winter Calgary can experience Chinook winds that warm the area.