Factors Driving Change In The Magnitude Of Water Stores 3112 Flashcards Preview

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Flashcards in Factors Driving Change In The Magnitude Of Water Stores 3112 Deck (29):

What water store has the longest residence years?

Oceans at 3600 years


Which water store has the shortest residence years?

Atmospheric water - 10 days


What is evaporation?

Energy from solar radiation hits the surface of water or land causing liquid water to change state from a liquid to a gas.


What is transpiration?

Water transported from the roots of a plant to its leaves and then lost through pores on the leaf surface.


Where does the majority of evaporation occur?

From oceans to the atmosphere


During evaporation why does the surroundings cool?

Because as water evaporates it uses energy in the form of latent heat and so the surroundings cool.


The rate of evaporation depends on three main factors, what are they?

1. The amount of solar energy
2. The availability of water (e.g there is more available water in a pond than in a grassy field)
3. The humidity of the air, warmer air can hold more water vapour than cold air.


Comment on the global evaporation rates.

Globally rates of evaporation over the ocean exceed terrestrial rates and this results in a transfer of atmospheric water to the continents as moist air moves across the continents driven by global air mass circulation.


What happens are air cools (in regard to water vapour)

It is able to hold less water vapour


What happens if the air is cooled sufficiently (in regards to water vapour)?

If the air is cooled sufficiently it will get to a temperature at which it becomes saturated. This is known as dew point temperature, excess water in the atmosphere will then be converted to liquid water in the process of condensation.


What do water molecules need to condense?

The need something to condense on, particles e.g smoke, salt, dust or surfaces e.g grass, stems) that are below the dew point temperature. If the surface is below freezing point then the water vapour sublimates (this means that the water changes directly from a glass to solid) in the form of hoar frost.


What is the direct cause of all precipitation?



What does precipitation do in terms of atmospheric moisture?

Returns atmospheric moisture to the terrestrial system.


What is the first cause of precipitation?

When the temperature of air is reduced to dew point but the volume remains consistent, this occurs when warm moist air passes over a cold surface or e.g on a cold winters night heat is hesitated to space and the ground gets colder, cooling the air directly in contact with it.


What is the second cause of precipitation?

When the volume of air increases but there is no addition of heat also known as adiabatic cooling. This happens when air rises and expands in the lower pressure of the upper atmsophere this can occur when:
- air is for ed to rise over hills (relief effect)
- masses of air of different temps and densities meet. the warm air rises over the cold air (frontal effect).
- when localised warm surfaces heat air above. This expands, becomes less dense and rises ( conventional effec.


What is the driving force behind global cloud formation and precipitation?

Global atmospheric circulation model.


After oceanic water what is the largest store of water on earth?

Water in a frozen form (ice)


What happens when snow falls on ice sheets and glaciers?

It becomes compressed and enters long-term storage, forming layers of glacial ice.


How many major glacial periods have there been?



What happens to sea levels during glacial period, and what is it called?

It is called the Quaternary glacial ion, started 2.58 million years ago. During glacial periods sea levels are much lower due to the volume of ice stored on land. During the last glacial period sea levels were 120m lower than present and continental glaciers covered large parts of Europe, North America and Siberia.


What is the time in between glacial periods called?

Interglacial periods when global ablation exceeds accumulation.


What are the five main variables that drive change in the magnitude of stores?

1) evaporation
2) condensation
3) precipitation
4) Cryospheric processes
5) runoff generation


What is an example of a Cryospheric process that affects the magi type on a shorter timescale?

Snow accumulated during winter adds to the ice sheet. In summer melting occurs or ice calves (breaks away). On a glacier, the equilibrium line marks the altitude at which accumulation and melting are equal. In recent decades the climate has warmed causing the equilibrium line to move to even higher altitudes. Most glaciers in the world are now shrinking and retreating


What effect does the melting of freshwater have?

It has s profound impact on sea levels, the total melting of all the polar sheets could result in a 60m rise in sea level, adding s great deal of water to the ocean store.


How are rising sea levels an example of positive feedback?

The removal of glacial ice (from melting) can destabilise glaciers and ice shelves leading to accelerated rates of ice calving.


What is runoff?

Surface runoff (also known as overland flow) is the flow of water that occurs when excess stormwater, meltwater, or other sources flows over the Earth's surface.


How does the time for runoff to reach the ocean vary?

Overland flow and river flow is relatively rapid whereas transit timed to the ocean for deep groundwater can be thousands of years.


How does infiltration affect runoff generation?

Infiltration is a key process in determining how much water runs off and how much wasted enters the soil as soil water storage through flow and then percolates to the bedrock to become groundwater flow.


Generally how is surface runoff generated?

When the rainfall intensity is greater that infiltration capacity or when rain falls on soils that are already saturated, understanding this is essential to effectively manage terrestrial water including managing flood hazards.