Factors driving change in magnitude of water stores

Residence time

The amount of water in a store divided by either the rate of addition of water to the store or the rate of loss from it.

why may water not remain in soil for long?

percolated into bedrock, transpired by plants, transferred into rivers by throughflow, evaporated

how does water move around?

energy as latent heat is absorbed or released depending on process. supplying or removing heat causes substance to change state, e.g. melting is supplying heat vs freezing is removing heat

Sublimation

The transition of ice to water vapour without a liquid stage.

Fusion

The substance changes from a solid to a liquid.

Freezing

The substance changes from a liquid to a solid.

Vaporisation

The substance changes from a liquid into a vapour.

Condensation

The substance changes from a vapour to a liquid.

Evaporation

Occurs when energy from the sun hits the surface of the water/land and causes liquid to change to a gas.

evaporation rate variables

amount of solar energy, availability of water, humidity (more humid has less evaporation), temperature of air

condensation- dew point

cooler air holds less water vapour, the temperature at which water vapour in the air turns into liquid water

What happens during condensation?

The temperature of the air is reduced to the dew point.

What causes the ground to cool on a cold winter's night?

Heat radiates away from the Earth.

What is adiabatic cooling?

It is the cooling of air as it rises and expands.

What is the orographic effect?

It occurs when air is forced over hills, leading to cooling.

cloud formation- step one

The atmosphere is full of gas particles known as water vapour. There are also tiny particles such as salt and dust these are called aerosols

cloud formation- step two

Water vapour and aerosols constantly bump into each other. When the air is cooled some of the water vapour sticks to the aerosols - this is condensation

cloud formation- step three

The warmer the air is the more water vapour it can hold. Clouds form when the air rises, becomes saturated and cannot hold any more water. This can happen in two ways: The amount of water in the air has increased or the air has cooled to its dew point

cloud formation- step four

Finally as water droplets group together they become heavy and gravity pills them down as raindrops. If the air is cold enough the ice crystals remain frozen and fall as snow

factors affecting cloud formation

spacial and temporal changes in the water cycle

What is the effect of the equator on cloud formation?

High evaporation, air rises, cools, and condenses to form a low pressure zone (ITCZ).

What happens in the mid latitudes regarding cloud formation?

Convergence of warm tropical air and cold arctic air.

What causes thunderstorms on a localized scale?

Intense convective activity.

cumulus cloud

heaped up/ puffy, low level

Stratus cloud

Flat/smooth, low level

Cirrus cloud

Wispy, high level - indicates a change in the weather will happen

Nimbus cloud

A rain-bearing cloud, low/medium level

Alto cloud

Ripple effect, medium level

frontal rainfall

Areas of warm and cool air are blown towards each other by the wind

The lighter, less dense warm air is forced to rise over the denser cold air

Frontal rain produces a variety of clouds which bring moderate to heavy rain

relief rainfall

The prevailing wind picks up moisture from the sea

The moist warm air is forced to rise, cools and condenses forming clouds

The air drops down over the mountain warming as it does. As it warms it increases the amount of water it can hold, meaning little rainfall occurs here. This is called the 'rain shadow effect

convectional rainfall

The surface of the earth is heated by the sun.

The warm surface heats the air above it. Hot air always rises and as it does so the air begins to cool and condensate

Convection produces cumulus-nimbus clouds (heavy, dark and towering storm clouds), which produce heavy rain and possible thunder and lightening

hill slopes

Hill slope is used to illustrate the processes at a local scale. They are

considered to be the most important local unit of study by hydrologists.

hill slope factors

consists of different types of water storage operating over short-time scales, magnitude of stores changes, most influential process is infiltration and rapid transfer of water overland causes flooding

soil water budget- field capacity

when the soil holds as much water as possible without any outputs occurring

soil water budget- winter months

precipitation exceeds potential evapotranspiration leading to a

water surplus, soils saturated, higher river levels and overland flow

soil water budget- summer months

evapotranspiration exceeds precipitation meaning that the soil dries up

soil water budget- autumn months

evapotranspiration starts to fall therefore soil water is replenished (recharged)

soil water budgets- variations

Soil water budgets vary considerably depending on the type and depth of the soil, its texture and permeability