Unit 4: Water Systems on Earth Water (Video) Grade 8 Science Unit 4: Water Systems on Earth Water (Video)

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

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

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

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

3. Freezing Point The temperature at which a liquid freezes. Fresh water... 0oC Salt water... -1.8oC

Three States of Water Water exists in three states, or forms. The three states of water are liquid, solid, gas.

Liquid Water Liquid water flows both above ground (surface water) and below ground. (under ground water) 1. Surface Water Surface water is found above ground. Rain and snow add to surface water all the time.

2. Underground Water Ground water is water that flows and pools underground in an area called the groundwater zone. In this area, water fills all the air spaces in the soil and rock. The upper part of the groundwater zone is called the water table. An aquifer is a reservoir, or large pool, of water that forms underground.

Solid All the solid water we find on Earth, such as ice and snow, is fresh water. As salt water freezes, at the water separates from the salt, becoming frozen fresh water. Solid water-mountain glaciers and ice sheets

Gaseous Water When water evaporates, it becomes a gas known as water vapour. Water vapour forms from oceans, lakes, and rivers. Water vapour rises and forms clouds. Animals put water vapour in the air when they exhale.

Homework 1. Draw, colour and label the diagram on pg 282 into your notebooks Define the key terms on page 277 Answer Q1-3 on page 283