22Jul
THE HYDROSPHERE.
All the water on the Earth forms the hydrosphere.
There are two types of water:
1. salt water
2. fresh water
- 97% of the water on the Earth is in oceans and seas. But this water is salt water and we can´t drik it or use it for agriculture.
´- 3% of the water on Earth is fresh water. Most fresh water is frozen in the ice caps and glaciers. Some fresh water is groundwater.
THE WATER CYCLE.
Water moves between the hydrosphere and the atmosphere. This process is called the water cycle.
Some salt water from oceans and seas changes to fresh water in the water cycle. When salt water evaporates, the salt stays in the sea and the water vapour contains only fresh water.
Clouds and precipitatio form from fresh water drops.
When the fresh water drops fall to the ground, some provide water for plants to frow and others collect in rivers and lakes. The water drops that collect in the sea become salt water again.
Fresh water is very limited so we shouldn´t water it or pollute it.
GROUNDWATER.
Groundwater is fresh water under the ground. Some grounwater has been under the ground for millions of year, but groundwater can also become surface water again too.
RIVERS
A river is a large, moving strem of fresh water which collects precipitation that drainsoff the nearby land. Rivers start at a source on high land and flow downhill following a course. A river can flow into a lake, another river of the sea or ocean. Rivers have different parts with different characteristics.
Rivers have different parts with different characteristics:
The upper course is on highland. The river flows through. the river is narrow and flows fast.
The middle course, the river is wider and there are small bends.It flows more slowly and starts to deposit stones.
The lower course the river flows across in a plain. It is very wide. The water moves very slowly. This is where the mouth is located. At the mouth of a river it can form a delta or estuary.
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