Grade 8 Science Unit 1: Water Systems on Earth

Effects of Water? Churchill River

Large Ocean Wave

How do you use water? House Hold Use Personal Use Recreational Activities

Water Distribution

Only 3% of the Earth’s water is fresh water (no salt). 2/3 of this water is frozen in ice sheets. Therefore only 1% of the fresh water on Earth is available.

Review of Terms... Definition of Lithosphere: the solid rocky ground of the Earth’s crust. Do not write in pamphlet

Atmosphere: the environment surrounding the Earth. Do not write in pamphlet

Hydrosphere: All water on Earth. Including that in the lithosphere and atmosphere.

Scientists who study water... Hydrologist A person who studies Earth’s water systems and helps to find solutions to problems of water quality and quantity. Not in pamphlet

Oceanographer: A person who studies all aspects of the ocean. They are concerned with the biology, geology, physics, and mathematics of the ocean.

Why do We Not Run Out of Water?? Because of the: WATER CYCLE

The Water Cycle...

The constant cycling of water through the processes of : Evaporation&Condensation.condensa tio Water is constantly changing from (gas liquid) and back again. This driven by the sun’s energy.

Ocean Water vs. Fresh Water Three ways in which fresh water differs from ocean water are: 1. Salinity 2. Density 3. Freezing point

1. Salinity - Definition -The amount of salt dissolved in a specific amount of water. salt comes from dissolved solids in the ground and volcanoes.

Fresh Water has tiny amounts of salt. Salt Water Average amount of salt in salt water is 35 ppt. Salt content varies depending on location. Increase salt at the equator and poles

2. Density - Definition -The amount of mass of a substance in a certain unit volume. * How tightly packed together the material is in a substance.

*Ocean water is more dense than fresh water due to the salt content. The Dead Sea

3. Freezing Point -Definition -The temperature at which a liquid freezes. * Fresh water... 0 o C *Salt water o C

Core Lab Activities Activity 1-3A “Salinity’s Effect on Water Density” Graphing Assignment pp60-61 “Temperature & Water Density”

Sources of Fresh Water 1. Lakes, ponds and wetlands 2. Streams and rivers 3. Ground water 4. Run Off 5. Glaciers

3. Ground Water... Precipitation that falls on land and sinks out of sight. Sinks through pores in rocks and goes down to bedrock where it pools. These pools to us make up “wells”.

Ground Water : Drilling Wells

4. Run Off Water that doesn’t sink into the ground or evaporate and flows over the land. Run-off is affected by: a) ground material, b) amount of rain, c) amount of time it rains, d) slope (steepness) of the land, e) vegetation, f) the amount of development.

GLACIERS

5.Glaciers... A moving mass of snow and ice. Found in areas where it is so cold the snow remains all year.

28 Glaciers A glacier is any large mass of ice that moves slowly over land. *Glaciers only form in areas where more snow falls than melts *Snow builds up year after year *Pressure on the snow at the bottom turns it into ice *Gravity pulls the glacier downhill

29 Types of Glaciers Valley glacier Continental glacier pubs.usgs.gov/of/2004/1216/images/mendenhall.gif

30 Types of Glaciers A valley glacier is a long, narrow glacier that forms high in a mountain valley *Also called Alpine glaciers *flows a few centimeters to a few meters per day A continental glacier is a glacier that covers much of a continent or large island *much larger than valley glaciers *spreads out like pancake batter *cover Antarctica and Greenland

Glaciers in mountains and on the continent of Antarctica

How Glaciers Move Glaciers flow until they reach an ocean, where crevasses open and icebergs fall off

Water trapped in glacial ice

Almost 69% of all fresh water on Earth is found in glaciers Glaciers slow down the Water Cycle by storing large amounts of frozen fresh water. (=Reservoir) Some water thaws in the hot summer months. Importance of Glaciers

Glaciers give us information about the Earth’s past climates. ( samples)

36 Continental Glaciers Continental glaciers cover about 10% of Earth’s surface ◦T◦T he glacier covering Antarctica is over 14 million square kilometers and 2 kilometers thick An Ice Age is a time when continental glaciers cover large parts of Earth’s surface * The last ice age ended 10,000 years ago. * Ice has covered 1/3 of Earth

The Ice Age The Ice Age The most recent began years ago ending years ago. Glaciers covered ~ 20% of land on Earth.

Glaciers and Global Warming Glaciers and Global Warming In the last 100 years the average surface temp. Has increased by 0.5 o C. The world’s glaciers are melting at a quicker paces than ever before.

Melting Greenland Glacier

Receding Athabasca Glacier in Alberta It has receded 1.5 km since 1843.

What does this mean? Ocean waters may rise Flood rivers If they disappear, rivers may dry up.

Watch the video Chasing IceChasing Ice

WATERSHEDS AND DRAINAGE BASINS

River System Vocabulary River Source Meander River mouth Delta Flood plain Tributary Divide Drainage basin Watershed

Watersheds The area of land with water that drains into a body of water such as a river, pond, lake or ocean. There may be many smaller basins within a larger basin. 6.Drainage Basins

Watersheds in NS Antigonish County… Antigonish – South, West River Afton, Monastery, Tracadie, Linwood – Tracadie River Havre Boucher – Tracadie River

Drainage Basins All of the water channels and tributaries that drain into a large river.

A divide separates one drainage basin from another. For example: The Continental Divide

Continental Divides (North America)

Canadian Drainage Basins

Drainage basins close to home are Labrador Sea, & Gulf Of St. Lawrence

CHARACTERISTICS OF WATER

One Component Affects Another Salinity : affects the types of organisms that can survive in an area. Eg. Dead Sea

Temperature : affects the amount of dissolved oxygen in water. Ex. The higher the temp. the more oxygen.

The convergence of the Labrador Current and the Gulf Stream Current (place where they meet) influences productivity of the Grand Banks (more fish there), the movement of icebergs, and migration of capelin and whales.