eduqas a level Geography- water cycle

is the water cycle open or closed

closed system

how much water is in the water cycle

1.38 million km3

what is the hydrosphere

all the water on earth in any form

what is the biosphere

all living organisms found on earth

what is the cryosphere

all areas of the earth where water is snow or ice

what is the lithosphere

the outermost part of the earth

what is the atmosphere

the layer of gas between the earths surface and space, held in place by gravity

what is permafrost

ground permanently frozen for over 2 years

what is eustatic change

global change in the volume of water in the oceans

what is accumulation

built up snow and ice in the cryosphere

what is ablation

change of ice into liquid or vapour

what is percolation

water moving through the ground rock layer into the groundwater layer belowwhat

what is surface runoff

unconfined flow of water over ground surface

what is transpiration

the exhalation of water vapour from the stomata of a plant

what is precipitation

water falling from clouds

what is evaporation

water removed from the surface of water taken into the sky

what is groundwater

water held underground in the soil

what is snowball

geologists believe earth may have become a giant snowball around 750-650 million years ago

what is hothouse process

around 65-35 million years ago hothouse conditions meant the poles were probably free of ice caps. global sea level higher

what did milankovitch specifically examine

how variations in three types of earths orbital movements affects how much solar radiation reaches the top of the earths atmosphere

what did the milankovitch cycles include

• the shape of the earths orbit (eccentricity)

• the angle of the earths axis tilted with respect to earths orbital plane (obliquity)

• the direction earths axis of rotation is pointed (procession)

what does eccentricity do to the seasons

slightly differs the lengths

what is currently happening with earths eccentricity

slowly decreasing and approaching its least ecliptic

what happens to glaciers and ice sheets during larger tilt angles

they favour periods of deglaciation so glaciers and ice sheets melt

what happens as obliquity/tilt decreases

makes seasons milder allowing snow and ice to build at high latitudes into ice sheets. these reflect energy back into space promoting further cooling

how doe precession affect the seasons

more extreme in one hemisphere and less extreme in the other

what causes the process of el nino

trade winds push warmer wate down and it builds up. cold water rises up. trade winds weaken which warm water to move east

what happens during el nino

warming of ocean surface

what does el nino tend to do

raise global temperatures

how often does the el nino process come about

every three to seven years

how will el nino affect 2024

2024 hurricane season likely wont have el nino to help weaken storms

what is the concept of mass balance within the hydrogical cycle

amount of water in the hydrological system is always conserved

why does the hydrological cycle conform to the rules of mass balance

transfers can occur eg changes in state

what is an input in the hydrological system

precipitation

what is a store in the hydrological cycle

ocean, groundwater, atmosphere, soil

what is a transfer in the hydrological cycle

surface runoff, cryosphere processes, percolation, evaporation, transpiration

what is outputs in the hydrological cycle

evaporation, transpiration

why is the system useful for understanding the global water cycle

allows simplification of complex processes

why is systems not useful in understanding the global water cycle

oversimplifies and gives incomplete picture- some elements may be missing

why is the global water cycle a closed system

inputs and outputs are at equilibrium

why is so little of the earths water available for human use

97% is saltwater which is unsafe for humans to drink

how does sea level change the amount of water stored in the oceans

ice melts increasing ocean store

how do changes to the cryosphere affect the amount of water stored

temperature increases so ice melts and evaporates. it is precipitated back into oceans

what are the processes that affect the transfers of water within the system

short term heavy rain

monsoon season and el nino increase rainfall

climate change increases ablation- transfers from cryosphere to hydrosphere

how much % of glaciers does antartica contain and what % of fresh water

91% of all glaciers

70% of earths fresh water

name a biome that contains permafrost

tundra

what happens to the ice in the arctic and how can this help scientists

sea ice forms

use it to see fluctuations in climate changewhat are

what are catchments

areas of land where runoff collects to a specific zone

what is a drainage basin

catchment area forming parts of the earths surface area which is drained by is drained by a particular stream or river

is drainage basin open or closed system

open system

what is throughfall

rainfall dripping from leaves and braches towards the ground

what is stemflow

water which flows to the ground via stems and trunks

what is infiltration

movement of water from the ground surface into the soil

what is throughflow

movement of water laterally through the soil via pore spaces

what is percolation

transfer of water from the soil into the underlying bedrock

what is groundwater flow

vertical and lateral movement of water through a drainage basins underlying rock due to gravity and pressure

what is overland flow

movement of a sheet of water across the ground

what is infiltration-excess overland flow

rainfall intensity is so great that not all water can infiltrate

what is saturation- excess overland flow

rainfall continues for a long time so entire soil becomes saturated

what is interception store

leaf and plants surfaces

what is vegetation store

water held in biomass itself

what is surface store

water collected on the ground in depressions and hallows

what is the soil moisture store

water held in soil pores space

what is the channel store

water held in the river channel itself

what is groundwater store

water stored in solid rock

what is river discharge

amount of water passing a given point

what is river discharge measured in

cumecs

what are temporal variations

changes over time

what is a simple regime

one high and one low discharge

what is complex regime

several extremes of discharge per year

how is lag time calculated

subtract peak discharge by peak rainfall

what is base flow

rain filling up the river from groundwater

how is the rising limb different to the falling limb

rising is water entering the river whereas falling is water leaving

how is the flood hydrograph an example of a temporal variation

changes to the river basin over a short period of time

what is a flashy hydrograph

short lag time, high peak discharge with steep rising and falling limb

what is a delayed hydrograph

long lag time low peak discharge

what are antecedent conditions

conditions of the weather and soil before the storm

what is circular basin

a rounded drainage basin where all points are equidistant from the river, leading to flashy hydrographs

what is elongated basin

stretched basin where some points in the basin are closer to the river than others leading to delayed hydrographs

what is the condensation nuclei

small dust or sea salt particles

why is warm air less dense than cold air

there is more space between the molecules

what is air uplift

air is less dense than the surrounding matter and hot air floats upward

what is convectional rainfall

when sun evaporates water from surface which leads to water vapour rising, cooling, condensing and forming rain

what is frontal rainfall

warm air rises over cold air, it expands, cools and condenses, clouds and rain form

what is orographic rainfall

warm air rises over a barrier, it cools and condenses forming form

what is collision coalescence process

water droplets form around condensation nuclei. they fall under gravity and collide with smaller droplets absorbing them

what is bergeron findeisen process

high altitude clouds contain ice crystals and super cooled water droplets. water evaporates off the droplets and deposits on the ice. ice crystals gain weight and fall as snowflakes. they melt in warmer layers and form rain droplets

what is excess runoff

flow of water that occurs when excess storm water, meltwater or other sources flows over the earths surface

what is runoff

all the rainwater that contributes to river discharge following a rainfall event

which drainage basin flows contribute to runoff

overland flow, throughflow and groundwater flow

how does storm activity lead to excess runoff

prolonged or high intensity precipitation

what are human causes of excess runoff

urbanisation makes ground impermeable, concrete and tarmac, drain and sewer network, less transpiration and interception without vegetation

what is water balance

balance between precipitation, evapotranspiration and runoff

what is water deficit

demand for water outweighs supply and there is less water than is required in that part of the water cycle

what is soil moisture recharge

when soil fills up with rainfall and is saturated

what is soil moisture utilisation

when rain in soil gets evaporated

what is soil moisture deficit

when there is not enough rainfall

what is soil moisture surplus

when there is too much rainfall and the soil is oversaturated

what is meteorological drought

an extended period of low or absent rainfall relative to the average for a region

what is agricultural drought

when there is insufficient moisture for average crop production