Processes Driving Change In The Magnitude Of Water Cycle Stores Over Time And Space

Question 1

Summary of what changes the size of stores in the global water cycle? (No examples)

Answer 1

Transfers/Flows which are processes, which determine how much water is inputted or outputted into the system. This may due to natural or anthropogenic (human) factors

Question 2

What are the main global transfer processes which change the magnitude of water cycle stores?

Answer 2

• Precipitation
• Evaporation
• Condensation
• Sublimation
• Interception
• Overland Flow
• Infiltration
• Throughflow
• Percolation
• Groundwater Flow
  (Also, climate change)

Question 3

Define Precipitation

Answer 3

Transfer of water from the Atmosphere to the ground. It can take the form of snow, rain, hail, dew

Question 4

Define Evaporation

Answer 4

Transfer of water from liquid state to gaseous state (water vapour). The vast majority occurs from the oceans to the Atmosphere

Question 5

Define Condensation

Answer 5

Transfer of water from a gaseous state to a liquid state, for example, the formation of clouds

Question 6

Define Sublimation

Answer 6

Transfer of water from a solid state (ice) to a gaseous state (water vapour)

Question 7

Define Interception

Answer 7

Water intercepted and stored on leaves of plants

Question 8

Define Overland Flow

Answer 8

Transfer of water over the land surface

Question 9

Define Infiltration

Answer 9

Transfer of water from the ground surfaces into soil, where it may then percolate into underlying rocks

Question 10

Define Throughflow

Answer 10

Water flowing through soil towards a river channel

Question 11

Define Percolation

Answer 11

Water soaking into rocks

Question 12

Define Groundwater Flow

Answer 12

Transfer of water very slowly through rocks

Question 13

Why does the magnitude of global water stores change over time and space?

Answer 13

For example, seasonal changes that occur in the Arctic with the annual freezing and melting of the sea ice
(caused by processes such as evaporation and Sublimation)

Question 14

How much does the global water stores change on a global scale?

Answer 14

Do not change significantly on a global scale

Question 15

How much does the water stores (e.g. Soil storage) change on a local scale?

Answer 15

Can change significantly on a local scale (e.g by extreme events such as storms)

Question 16

Describe Evaporation generally and on a Local and Global Scale

Answer 16

• Approx. 90% of atmospheric water storage is from evaporation of oceans and seas
• 10% comes from plant transpiration
• High levels of Evaporation can occur in tropical and desert areas (regional level)
• Increased global changes due to Evaporation are likely to occur due to climate change and increased atmospheric temperature
• Level of Evaporation on global scale for Ocean and sea level is minimal, but in drainage basin (local) Evaporation has large impact
• Lakes/rivers in areas with high maximum summer temperature experience high levels of Evaporation, so Hydrosphere storage will reduce significantly (causing droughts)

Question 17

Describe Condensation

Answer 17

• Occurs when temperatures fall and humidity increases
• Tiny, microscopic water molecules which develop around dust and smoke particles (called aerosols) will be carried on the area invisibly. When they combine into larger molecules of liquid water or ice, they may be mist, fog or clouds
• This occurs on a global scale but could alter as climate change increases global atmospheric temperatures

Question 18

Describe Cloud Formation

Answer 18

• Process where clouds form when water molecules aggregate
• Occurs when air temperature falls to a point where condensation of water vapour occurs (at dew point) or when humidity content has risen (so that water vapour can’t remain in that state and condenses)
• As water molecules aggregate, clouds form with tiny water/ice particles kept in the air by rising air currents

Question 19

Describe causes of precipitation

Answer 19

• Occurs when water molecules within a cloud combine and become too large (called coalescence)
• Occurs of the droplet’s fall velocity is greater than the cloud’s updraft velocity (if droplets fall faster than the cloud moving upwards)
• Whether rain, snow or hail is the precipitation depends on the clouds surrounding temperature and height

Question 20

Describe Cryospheric Processes

Answer 20

• After oceanic water, the largest store of water on Earth is frozen water (ice) in the Cryosphere
• 95% of frozen water is stored in the world’s two largest ice sheets covering Antarctica and Greenland
• 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 temperatures
• During cold global periods, inputs are greater than outputs in the Cryosphere (water is transferred to Cryosphere as snow and less water transferred away due to melting)
• During warm global periods, magnitude of Cryosphere Store reduces as losses due to melting are larger than inputs of snow
• On a long-time scale, snow falling on glaciers and ice sheets become compressed and enter long-term storage, forming layers of glacial ice (scientists have found ice over 400,000years in Antarctic)
• On short time scale, snow accumulated during winter adds to mass of glacier or ice sheet. In summer, melting occurs or ice calves (breaks away). On a glacier, the equilibrium line marks the altitude where annual accumulation and melting are equal.
  Recently, climates have warmed causing the equilibrium lines to move to higher altitudes, most glaciers are shrinking and retreating

Question 21

Example of Positive Feedback of melting freshwater ice

Answer 21

Melting of freshwater ice –> increases sea levels (total melting of all polar ice sheets can result in a 60m rise in sea level) –> increases water to the ocean store (Hydrosphere)