THE HYDROSPHERE.

The Earth’s water.

Hydrosphere is the combination of all the waters to be found on Earth. It includes:

Marine waters (oceans and seas), represent about 97’5% of the Earth’s waters and covers about 70% of the Earth’s surface.

Continental waters, most of them are fresh waters and represent  a 2’5% of the Earth’s waters. Includes rives, lakes, glaciers and aquifers.

Marine waters.

We can distinguish two types of marine waters:

Oceans are large masses of salt water. There are five oceans in order of size are:the Pacific, the Atlantic, the Indian Ocean, the Arctic and the Antarctic.

Seas, are áreas of the oceans that:

-Are close to the coastline.

-Shallower than the rest of the ocean.

For historical or cultural reason have their own names.

The water of the oceans has two main characteristics:

1.It is salt water, has sodium chloride disolved in it.

2.It is constantly moving. Has several kind of movements:

-waves, the undulating movement on the sea’s surface caused by the wind.

-tides, the rise and fall of the sea level caused by the Moon.

-marine currents, movements of large masses of water through the oceans. 



Are caused by two factors:

1.  The difference of temperature and salt levels of the oceanic waters. 
2. The wind.

Can be:

• Warm and cold, depending on wheter the temperature of the water that flow through it is lower or higher than the temperature of the water surrounding it.
• Surface or deep-sea depending of its depth.

A message in a bottle found three years and 5.000 kilometres later.
Experiment about water temperature and salinity.

Continental waters:

Most of the continental waters are fresh waters. Among them we can distinguish several types:

• Glaciers, large acumulation of frozen water. Most of them are located in Greenland, the Antarctica and high mountains.Them have two main parts:

1. Cirque, a steep bowl-shaped depression which form the head of the glacier.
2. Tongue, a narrow extension of ice projecting from the glacier cirque.

• Rivers are continuous currents of water that flow along a course. Most of them begin as springs and are supplied by rainfall or melting snow. Can flow into the sea or another river. We can distinguish three parts in the course of a river:

1. Upper course, the river flows in the mountains. Here flows very fast.
2. Middle course, the river flows through flat lands. The speed of the current is slower and the current of the river bends, forming meanders. A meander, is a bend in the course of the river formed by the accumulation of sediments.
3. Lower course, the river flows into the sea.

Upper course.

Middle source.

Lower course

• Lakes, are acumulations of water in low-lying areas of the Earth's crust. The water is supplied by rainfalls or rivers. We can also distinguish:

1. Lagoons, small lakes.
2. Seas, huge lakes such as the Caspian Sea.

Caspian Sea, the largest lake in Earth.

• Aquifers, are subterranean reserves of water, formed by the infiltration of water from the Earth's surface.

The water cycle.

The water cycle is the state of permanent circulation of the Earth's water. Water in Earth appears in the three states: liquid, solid (ice) and gaseous  (water vapour).

The fundamental processes of this cycle are:

• Evaporation, the change of water from a liquid to a gas (water vapour). Solar energy causes the evaporation of the surface water of the oceans and continental waters (lakes, rivers, etc.). 

• Condensation: Water vapour rises, cools, condenses and form clouds which are transported by the wind.
• Precipitation is the fall of the water onto the Earth’s surface in the form of rain, snow or hail. Is caused by the condensation of the water inside the clouds. When the clouds go up, water vapour cools and little drops of water appears. This drops combine with one another and when they reach a diameter of 0.5 mm fall to the ground.

A part of this water falls again into the oceans, but another part falls on the Earth, of this:

• A part filters into the subsoil and forms aquifers (infiltration). Sometimes the water of the aquifers reaches the surface trough a spring.

Water spring.

• Other remains on the surface forming rivers and lakes.

Finallly, the rivers and the aquifers run into the oceans and the cycle stars again.

The water cycle is a constant and balanced process. The total amount of evaporation and precipitation are compesated and as a consequence the quantity of water on the planet remains constant.

Water cycle.

Water consumption. Note: 1 gallon=4 litters
Water scarcity

ACTIVITIES:

1. Fill the blank spaces with the correct words:

The oceanic waters has three kind of movements: ______, _____ and ______  _______. A _____ is

a _________  movement of the sea's _______ caused by the ____.The ____ are the change of the
____ _____ caused by the ___________ pull of the ____. The _____  ______ are the ________ of 

huge masses of _____ inside the oceans caused by the ____ and the differences of ________ and

_________ between the different parts of the oceanic waters.

2.Complete the diagram with the correct words.
 

You can find the answers here.