CTMA 2nd years Bilingual Baccalaureate

The Water Cycle

1. Use next words and expressions to fill in the gaps in the text below. After finishing, define the words.

aquifer clouds condensation dew point

evaporation groundwater hard water hydrologic cycle

hydrosphere fertilizers detergents pollution

precipitation runoff saltwater intrusion saturated

sinkhole soft water spring river mouth

transpiration water table fresh water well

More than 70 percent of planet Earth’s surface is covered by water. This 70 percent of the surface includes oceans, lakes, rivers, and other bodies of water. Water circulates among these sources in a cycle powered by the sun. This water cycle is essential to all life. In Murcia, water is of extreme importance. The only permanent river in the region is the river Segura. But there is little water in the river, and it is polluted from Archena to the ............................. There are some aquifers which are being used to extract water; Most of them are being overexploited because the amount of water extracted exceeds the natural extra water recovered.

The ............................... is formed by all of Earth’s water. The oceans contain over 95 percent of Earth’s water supply; however, its water is salty and cannot be used directly by people to drink and grow food. Earth’s usable freshwater supplies are found in moving water such as rivers, streams, and springs, and in standing water in ponds, lakes, and wetlands. Much of our freshwater supply is frozen in polar ice caps and glaciers.

Water moves from oceans and freshwater sources to the land and air and then back to the oceans in a continuous cycle called the .................................... The water cycle provides fresh, usable water to lands all over the world. The water cycle changes salty, unusable ocean water into fresh, usable water. The water cycle has three main steps.

The first step involves the .................................. of water into the air. Evaporation is a process in which water changes from its liquid state to a gaseous state called water vapour. Most of this occurs when the sun heats the water in oceans, lakes, and other bodies of water, causing evaporation. Plants also give off water vapour from their leaves in a process called transpiration. Animals, too, give off water vapour as part of respiration.

In the second step of the water cycle, the water changes back into a liquid during a process called ................................................. This occurs because water vapour cools as it rises in the atmosphere. The temperature at which water condenses is called the ............................. . At the dew point, water condenses into tiny droplets and may form clouds.

The third and last step of the water cycle is ................................... This is when the fresh water returns to Earth as rain, snow, rain, hail or fog. Some of the water that returns to Earth will run and accumulate into the oceans, lakes, and rivers. This water is called .................................. The rest of the water filters into the ground and becomes ................................... Eventually, the groundwater will return to the ocean through underground channels, where it will continue in the water cycle.

Seawater is not pure water. It contains salts and other chemical compounds. All of the salts in ocean water were carried from the land to the sea by rivers or runoff. The salinity is the amount of dissolved substances in seawater. Most seawater has a salinity of about 3.5 percent or 35 parts per thousand. Salinity of seawater increases as water is evaporated by the sun because the salts are left behind.

Water that filter into the ground is called .................................. Different types of rocks and soil hold different amounts of groundwater. Ground that has many pores or spaces between the soil particles can hold a lot of groundwater. When all of the pores and spaces are filled with water and the ground has all the water that it can hold, it is said to be ........................... The upper level of the saturated zone of groundwater is called the .................. When you dig a ................... to get water, you must dig below the level of the water table to get water to flow up through the well.

................................. are layers of rock found underground that have large pores and through which water can easily move. Most aquifers are made of sand, gravel, sandstone, or limestone. Most of the time you must use a pump to get the water from an aquifer. However, sometimes when a well is dug, there is enough pressure to cause the water to flow to the surface on its own. This is an artesian well. When water reaches the surface under pressure and flows out of natural openings in the rock, a ................. is formed. Geysers are springs in which the water that flows out is hot.

Groundwater dissolves certain types of minerals, such as limestone, and carries them away, leaving hollow chambers or underground caves. Occasionally, during dry periods when the level of the groundwater is very low, the roofs of these caves may collapse, forming .................................. When the water table returns to its normal level, the sinkholes fill with water and become lakes or ponds.

Rainwater that does not contain any dissolved minerals is called ........................... When the rainwater filters through the ground, it dissolves calcium carbonate from limestone and becomes hard water.

Aquifers which are near the sea when are overexploited may suffer from ........................................................ This is when salt water moves into the freshwater aquifer. This can contaminate the water supply reducing the amount of fresh water available. Other factors that affect freshwater systems are pollutants. Phosphates, found in ..................................... and fertilizers, and nitrates from animal wastes and ............................, are two major causes of water pollution. Other pollutants may come from non- depurated urban water. These pollutants kill fish and plant life and make water unsafe for drinking.

Tuesday, 17 January 2012

Sunday, 15 January 2012

LA TIERRA ARRUGADA POR LA GRAVEDAD

Friday, 9 December 2011

Jenny¨s class: The water cycle

Thursday, 8 December 2011

CRISIS SÍSMICA DE 2011 EN EL HIERRO:

Friday, 2 December 2011

PRUEBAS PAU CTMA