Grade 8 Science Unit 1: Water Systems on Earth Chapter 1
Effects of Water? Churchill River
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... Do not write in pamphlet Definition of Lithosphere: the solid rocky ground of the Earth’s crust.
Do not write in pamphlet Atmosphere: the environment surrounding the Earth.
Hydrosphere: All water on Earth. Including that in the lithosphere and atmosphere.
Scientists who study water... Not in pamphlet Hydrologist A person who studies Earth’s water systems and helps to find solutions to problems of water quality and quantity.
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 constant cycling of water through the processes of : Evaporation&Condensation.condensatio 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 - Definition salt comes from dissolved solids in the ground and volcanoes. salt comes from dissolved solids in the ground and volcanoes. -The amount of salt dissolved in a specific amount of water.
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.
3. Freezing Point -Definition -The temperature at which a liquid freezes.
Core Lab Activities Activity 1-3A “Salinity’s Effect on Water Density” Graphing Assignment pp60-61 “Temperature & Water Density”
Sources of Fresh Water Lakes, ponds and wetlands Streams and rivers Ground water Run Off Glaciers Drainage Basins
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”.
4. Run Off • doesn’t sink into the ground or evaporate.: flows on land. • 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.
5.Glaciers... A moving mass of snow and ice. Found in areas where it is so cold the snow remains all year.
Glaciers slow down the Water Cycle by storing big amounts of frozen fresh water. Some water thaws in the hot summer months. • They give us information about the Earth’s past climates. ( samples)
The Ice Age The most recent began 120 000 years ago ending 11 000 years ago. Glaciers covered ~ 20% of land on Earth.
Glaciers and Global Warming In the last 100 years the average surface temp. Has increased by 0.5oC. The world’s glaciers are melting at a quicker paces than ever before.
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.
6.Drainage Basins • 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.
Adivide separates one basin from another. For example: The Continental Divide
6 Major Drainage Basins in NL Labrador Sea Gulf of St. Lawrence West Coast Gulf of St. Lawrence South Coast Gulf of St. Lawrence Atlantic Ocean Avalon Peninsula Atlantic Ocean North-east Coast