UNIT 3. THE HYDROSPHERE

1. HYDROSPHERE

• As you know, three quarters of Earth´s surface is covered by water, one of the essential conditions which determine the existence of life in Earth.

• The word hydrosphere refers to all the water on the planet, in all states:

– Solid.– Liquid.– Gas.

TYPES OF WATER: STATES

SOLID STATE WATER• Most solid state water exists as snow and

ice in the polar ice caps and glaciers. • Liquid water freezes below 0 °C and

transforms into a solid.GLACIERS

Are large, semi-permanent bodies of

solid water, such as The Perito Moreno Glacier

(Argentina) or Petermann Glacier (Greenland).

LIQUID STATE WATER• Most liquid water is seawater (aguas marinas) which is found in

oceans and seas. A small percentage is inland water (aguas continentales), which is made up of both surface water (lakes and rivers) and groundwater (underground water layers, known as aquifers).

Water exists in a liquid state between 0 °C and 100 °C.

All liquid water contains some salt, but it can be split into three different types, depending on the salt level:

• Fresh water: very low salt content (inland water).• Brackish water: moderate salt content (inland water:

mangroves, estuary, marshland…).• Salt water: high salt content (seawater).

GAS WATER STATE

• Water is considered a gas in the form of water vapour. Most water vapour exists in the Earth’s atmosphere as evaporation from surface water. However, it can also come from inside the Earth in areas of volcanic activity.

Underground water vapour escapes from the Earth

through volcanic geysers

WATER CYCLE• The water cycle or hydrologic is a continuous cycle

where water evaporates, travels into the air and becomes part of a cloud, falls down to Earth as precipitation, and then evaporates again. This repeats again and again in a never-ending cycle.

WATER CYCLE SONG: https://www.youtube.com/watch?v=TWb4KlM2vts&feature=youtu.be

WATER DISTRIBUTION:WATER IN SEAS AND OCEANS AND INLAND WATER

WATER IN SEAS AND OCEANS → SALT WATER.OCEANS are large bodies of water that surround continents. SEAS are smaller. They are partly surrounded by land and form parts of oceans.

COMPOSITION: sea water is a mixture of mineral salts, such as sodium chloride (common salt) and magnesium salts.

– The salt in sea water affects density: water with a higher salt content has a greater density.– Seawater temperature depends on latitude and depth. In lower altitudes (more exposed to sunlight), are

warmer. Temperatures are lower in deeper bodies of water and warmer in shallower areas.

MOVEMENT. Oceans and seas move and change all the time in a variety of ways:

– Waves: occurs on the surface of the water, mainly caused by the wind.– Tides: are the regular movements of the seas in which the sea levels rise (high tide -

pleamar) and fall (low tide - bajamar). – Ocean currents: are horizontal movements of water within the oceans and seas. There are

warm currents and cold currents.

INLAND WATER → FRESH WATER.• Inland water includes surface water and groundwater, as well as glaciers.

1. Surface water can be found on Earth in a variety of forms:1. Rivers: are flowing body of fresh water. The route of a river is called its course.2. Lakes: a body of fresh or salt water of considerable size, surrounded by land.3. Wetlands: a shallow layer of water covers the ground for only part of the year.4. Glaciers: are large masses of slow-moving ice.

2. Ground water: is water that is stored underground, beneath the surface of the Earth.

1. Well.2. Ground water accumulates

from rainwater.3. Springs.4. Impermeable material.5. Water table.6. Aquifers.

V-shaped valley (River)

U-shaped valley (Glacier) Moraines