The Global Water Cycle (Booklet 2)

Question 1

What is the process of a solid (e.g. ice) vhanging to liquid (e.g. water) called?

Answer 1

Melting which uses latent heat

Question 2

What is the process of a liquid (e.g. water) changing to a gas (e.g. vapor) called?

Answer 2

Evaporation which uses latent heat

Question 3

What is the process of a solid (e.g. ice) changing to a gas (e.g. vapor) called?

Answer 3

Sublimation which uses latent heat

Question 4

What is the process of a gas (e.g. vapor) changing to a liquid (e.g. water) called?

Answer 4

Condensation which releases latent heat

Question 5

What is the process of a liquid (e.g. water) changing to a solid (e.g. ice) called?

Answer 5

Freezing which releases latent heat

Question 6

What is the process of a gas (e.g. vapor) changing to a solid (e.g. ice) called?

Answer 6

Deposition which releases latent heat

Question 7

Which changes in state use latent heat?

Answer 7

Melting, Evaporation & Sublimation use latent heat

Question 8

Which changes in state release latent heat?

Answer 8

Consensation, Freezing & Deposition release latent heat

Question 9

What do all of the changes in state involve?

Answer 9

All changes in state involve heat energy (latent heat)

Question 10

What are clouds and what do they do?

Answer 10

Clouds are condensed water vapour which clean the atmosphere of tiny specks of dust

Question 11

Why is cloud formation and precipitation essential?

Answer 11

Cloud formation and precipitation are essential parts of the water cycle as precipitation is the main flow of water from the atmosphere to the ground.

Question 12

When do clouds form?

Answer 12

Clouds form when warm air cools down, which causes the water vapour in it to condense into water droplets, which gather as clouds. When the droplets get big enough, they fall as precipitation.

Question 13

What causes the warm air to cool which leads to precipitation?

Answer 13

There are several things that can cause warm air to cool, leading to precipitation and these include:
- Other air masses
- Topography
- Convection

Question 14

What are other air masses?

Answer 14

Other air masses can cause precipitation to occur as the warm air in the atmosphere is less dense than the cool air. As a result, when warm air meets cool air, the warm air is forced up above the cool air. It cools down as it rises. this results in frontal precipitation.

Question 15

What is topography?

Answer 15

Topography occurs when warm air meets mountains, it’s forced to rise as the hills almost act as a barrier, causing it to cool and form clouds. This results in orographic/relief precipitation.

Question 16

What is convection?

Answer 16

Convection occurs when the sun heats up the ground, which causes moisture on the ground to evaporate and rise up in a column of warm air. As it gets higher, it cools. This results in convective/convectional precipitation.

Question 17

Why can’t water droplets form clouds on their own?

Answer 17

Water droplets caused by condensation are too small to form clouds on their own. For clouds to form, there have to be tiny particles of other substances (e.g. dust or soot) to act as cloud condensation nuclei/hydroscopic nuclei. They give water a surface to condense on. This encourages clouds to form, rather than allowing the moist air to disperse.

Question 18

How do cloud formation and precipitation vary?

Answer 18

Cloud formation and precipitation can vary seasonally (e.g. in the UK there’s normally more rainfall in winter than in summer) and by location (e.g. precipitation is generally higher in the tropics tham at the poles).

Question 19

In which form is water stored in the water cycle?

Answer 19

Water is stored in Solid, Liquid and Gas forms

Question 20

How much water does the hydrosphere contain?

Answer 20

The hydrosphere contains 1.4 sextillion litres of water

Question 21

Where is water stored on Earth?

Answer 21

Water is stored within four major physical systems - the lithosphere (land), hydrosphere (liquid water), cryosphere (frozen water - snow and ice) and in the atmosphere (air).

Question 22

What is the definition of the oceanic water store?

Answer 22

The oceans are the biggest stores of water (saline) they dominate the amount of water available with just over 97% of all of the water being found in the oceans.

Question 23

What is the definition of the cryospheric water store?

Answer 23

The cryopshere includes all of the frozen water in the Earth’s system. This means the frozen parts of the ocean, so water can be stored in glaciers, ice shelves, ice sheets, ice caps and permafrost.

Question 24

What is the definition of the terrestrial water store?

Answer 24

the terrestrial water store includes surface water, ground water, soil water & biological water, rivers and lakes are the most accessible in the terrestrial system.

Question 25

What is the definition of the atmospheric water store?

Answer 25

Most of the water stored in the atmosphere is found in the gaseous state, water vapour which is a colourless and odourless gas. Atmospheric water absorbs solar energy, redistributes wateraround the globe and also removes impurities from in the air.

Question 26

What is the biggest store of water on Earth?

Answer 26

Most of the water on Earth is saline water (97.4%) and it is stored in the oceans.

Question 27

What percentage of the Earth's water is freshwater?

Answer 27

Only 2.5% of the Earth's water is freshwater: - 69% is frozen in the cryosphere - 30% is groundwater (water stored underground in the lithosphere). - 0.3% is liquid freshwater on the Earth's surface in lakes, rivers etc. - 0.04% is stored as water vapour in the atmosphere.

Question 28

What must water be for humans to be able to use it?

Answer 28

Water must be physically and economically accessible for humans to be able to use it (e.g. groundwater is hard to access, so it may not be cost effective to extract it). As a result, only a small amount of water on the planet can be used by humans.

Question 29

What can water change between?

Answer 29

Water can change between solid, liquid and gaseous forms. For water to boil or melt, it has to gain energy (e.g. from the sun). For water to condense or freeze, it has to lose energy.

Question 30

What is the definition of sea ice?

Answer 30

Sea ice is frozen seawater that floats on the ocean surface it must be extremely cold to form as the salty ocean water means that it freezes at a lower temperature. It forms in both the Arctic and the Antarctic.

Question 31

What is the definition of an iceberg?

Answer 31

An iceberg is ice that broke off from glaciers or shelf ice and is floating in open water. Most icebergs are near greenland and some are found in Alaska

Question 32

What is the definition of an ice sheet?

Answer 32

An ice sheet is a mass of glacial land ice which extends more than 50,000 square kilometres. Important examples include the Antarctic Ice sheet and the Greenland ice sheet.

Question 33

What is the definition of an ice shelf?

Answer 33

Ice shelves are floating extensions of ice that extend from glaciers grounded on land. They are found along the coasts of the two remaining ice sheets in Greenland and also Antarctica.

Question 34

What is the definition of permafrost?

Answer 34

Permafrost is any ground that remains completely frozen for at least two years straight and it occura in Northern Greenland, Canada, Russia, Alaska and the Himalaya.

Question 35

What is the definition of an ice cap?

Answer 35

An ice cap is a thick layer of ice and snow that covers large areas of land under 50,000 kilometres. One Ice cap covers most of Greenland and the other spans across the continent of Antarctica.

Question 36

What is the global hydrological cycle?

Answer 36

The Global hydrological Cycle/The Global Water Cycle is a closed system as there are no inputs or outputs of water. It is driven by energy from the sun and the system is in dynamic equilibrium. The cycle involves water continuously being cycled between different stores.

Question 37

What is the definition of an aquifer?

Answer 37

An aquifer is an underground store of water that can be used as a resource for fresh drinking water.

Question 38

What is the definition of residence time?

Answer 38

Residence time refers to how much time water tends to spend in a store.

Question 39

What is the residence time of groundwater like?

Answer 39

The residence time of groundwater is very long (from 2 weeks to 10,000 years) as it cannot be evaporated into the atmosphere from underground. However this depends on how far the water is underground as the residence time can vary.

Question 40

What is the typical trend between residence time and the size of the store?

Answer 40

Typically some of the biggest stores of water have the longest residence times. However, there is a large variation and range in the residence times of the stores of water.

Question 41

How does the amount of water in a store vary?

Answer 41

The amount of water present in each store varies over a range of scales from local (e.g. an individual hillslope) to global. The magnitude of each store depends on the amount of water flowing between them and different flows/transfers occur at a range of spatial and temporal (time) scales.

Question 42

Which spatial and temporal factors affect evaporation and therfore impact the magnitude of the water cycle stores?

Answer 42

Evaporation occurs when liquid water changes state into a gas, becoming water vapour - it gains energy, normally from solar radiation. Evaporation increases the amount of water stored in the atmosphere: - the magnitude of the evaporation flow varies by location and season. If there is lots of solar radiation, a large supply of water and warm, dry, air, the amount of evaporation will be high. - If there is not much solar radiation, little available liquid water and cool air that is already nearly saturated (unable to absorb any more water vapour), evaporation will be low.

Question 43

Which spatial and temporal factors affect condensation and therfore impact the magnitude of the water cycle stores?

Answer 43

1) Condensation occurs when water vapour changes state to become a liquid - it loses energy to the surroundings. It happens when air containing water vapour cools to its dew point (the temperature at which it will change from a gas to a liquid), e.g. when temperatures fall at night due to heat being lost to space. 2) Water droplets can stay in the atmosphere or flow to other subsystems, e.g. when water vapour condenses, it can form dew on leaves and other surfaces - this decreases the amount of water stored in the atmosphere. 3) the magnitude of the condensation flow depends on the amount of water vapour in the atmosphere and the temperature. For example, if there is lots of water vapour in the air and there's a large or rapid drop in temperature, condensation will be high.

Question 44

Which spatial and temporal factors affect cryospheric processes and therfore impact the magnitude of the water cycle stores?

Answer 44

1) Cryospheric processes such as accumulation and ablation change the amount of water stored as ice in the cryosphere. the balance of accumulation and ablation varies with temperature. 2) During periods of global cold, inputs into the cryosphere are greater than outputs - water is transferred to it as snow, and less water is transferred away due to melting. During periods of warmer global temperatures, the magnitude of the cryosphere store reduces as losses due to melting are larger than the inputs of snow. 3) The Earth is emerging from a glacial period that reached its maximum 21000 years ago. There are still extensive stores of ice on land in Antarctica and Greenland, as well as numerous alpine glaciers. there is also a large volume of sea ice in the Arctic and Antarctica. 4) Variations in cryospheric processes happen over different timescales. As well as the changes in global temperature that occur over thousands of years, variations can also occur over sjorter timescales. For example, annual temperature flucuations mean that more snow falls in the winter than in summer.

Question 45

Where is there less cloud coverage on Earth?

Answer 45

There are less clouds in areas where there are deserts e.g. Antarctica and The Sahara because they are areas of high pressure where the air is sinking and not rising to form clouds.

Question 46

Where is there more cloud coverage on Earth?

Answer 46

There are lots of clouds at 60 degrees North and South of the Equator as it is an area of extreme low pressure where the air is rising to form clouds e.g. cumulonimbus.