Physical Geography A-Level

Adaptation

adjustments in ecological, social or economic systems in response to actual or expected climatic stimuli and their effects.

Mitigation

preventing or reducing the emission of greenhouse gases (GHG) into the atmosphere to make the impacts of climate change less severe.

Revegetation

using improved pasture species and legumes. This increase productivity, producing more plant litter and underground biomass (adding to the soil organic carbon).

Irrigation & Water Management

can improve plant productivity and production of soil organic carbon.

Mulching

a covering (as of straw or sawdust) spread over the ground to protect the roots of plants from heat, cold, or evaporation, prevent soil loss, control weeds, enrich the soil, or keep fruit (as strawberries) clean.

Agroforestry Systems

land use systems in which woody plants (trees or shrubs) are combined with crops and/or animal husbandry on one area

Drainage Basin

the area of land around the river that is drained by the river and its tributaries

Positive Feedback

Positive feedback loops enhance or amplify changes; this tends to move a system

away from its equilibrium state and make it more unstable.

Negative Feedback

Negative feedbacks tend to dampen or buffer changes; this tends to hold a system

to some equilibrium state making it more stable.

Input / sources

Where matter or energy is added to the system.

Outputs

Where matter or energy leaves the system.

Stores / sinks

Where matter or energy builds up in the system.

Transfers / flows

Where matter or energy moves in the system.

Energy

power or driving force e.g. latent heat associated with changes in the stet of water

Dynamic equilibrium

lack of change in a system as inputs and outputs remain in balance.

Sediment sources

Places where sediment is generated.

Cells and Bridgets

A stretch of coastline where a complete cycle of littoral transportation and sedimentation occurs

Weathering

the wearing down or breaking of rocks while they are in place.

Mass movement

processes of erosion, transport and accumulation of material that occur on both gentle and steep slopes mainly owing to gravitational forces.

Erosion

the geological process in which earthen materials are worn away and transported by natural forces such as wind or water.

Transportation

the movement of material across the Earth's surface by water, wind, ice or gravity.

Deposition

the laying down of sediment carried by wind, flowing water, the sea or ice.

Hydraulic Action

the sheer force of water crashing against the coastline causing material to be dislodged and carried away by the sea.

Wave Quarrying

when high energy, tall waves hit the cliff face they have the power to enlarge joints and remove large chunks of rock in one go through vibration.

Abrasion/Corrasion

when pebbles grind along a rock platform, much like sandpaper.

Cavitation

The caving-in of bubbles in a liquid, close to a solid surface, causing shock waves.

Solution

when sea water dissolves certain types of rocks.

Attrition

Rocks and pebbles are carried in the flow of a river, they repeatedly knock into each other, which causes the rocks to erode or to break. As the rocks continue to collide, they erode more and more, getting smaller and smaller until they are only sediment.

Traction

a method of transportation for large stones or boulders in a river.

Suspension

a method of transporting very fine sediment in a river.

Longshore Drift/Littoral Drift

The movement of material, such as sand and stones, along a coastline caused by the movement of waves.

Sub-Aerial Weathering

weathering by rain, frost, rivers etc.

Runoff

precipitation that runs off the landscape

Tidal Currents

the periodic horizontal flow of water caused by the rise and fall of tides.

Longshore Currents

When a wave reaches a beach or coastline, it releases a burst of energy that generates a current, which runs parallel to the shoreline.

Rip Currents

a powerful, narrow channel of fast-moving water that flows from the shore out to the sea.

Upwelling

a process in which deep, cold water rises toward the surface.

Afforestation

the planting of trees on land that has never had forest, or has been without forest for a long time

Agricultural Drought

a rainfall deficiency from meteorological drought that leads to deficiency of soil moisture and soil water availability, which has a knock on effect on plant growth and reduces biomass

Aquifer

A permeable or porous rock which stores water

Base Flow

Water stored in rivers, streams, lakes and groundwater in liquid form (the visible part of the hydrological cycle)

Boundaries

Limits of the system

Elements

The things that make up the system of interest e.g. plants, animals, rain droplets

Attributes

the perceived characteristics of the elements e.g. size, colour, temperature

Relationships

description of how the elements (and their attributes) work together to carry out the process (cause and effect)

Morphological Systems

simplest form of system, in which some of the component parts or elements are identified, and the links between them are shown

Cascading Systems

characterised by the way energy or matter flow through it

Process-Response System

Integrates some of the characteristics of both morphological and cascading systems

Open Systems

a system in which both mass and energy are allowed to transfer across system boundary. There may be flow of matter as well as energy into or out of the system e.g. the drainage basin hydrological cycle e.g. Earth in regards to energy

Closed Systems

There is transfer of energy but no matter across the external boundaries of the system e.g. the global hydrological cycle system e.g. Earth in regards to matter

Isolated Systems

There is no interaction between the system and its surroundings. Practically, these type of systems do not exist and so are only theoretical

Subsystem

a smaller part of a large system e.g. the basin hydrological cycle is a subsystem within the larger Earth-ocean-atmosphere system

What are the 5 different subsystems?

lithospere, atmosphere, hydrosphere, cryosphere, biosphere

Equilibrium

A state of balance between inputs and outputs. The precise nature of any equilibrium depends on the timescale involved

Steady state equilibrium

there is balance in the long term, although there may be short-term changes e.g. longer-term cyclical variations in river flow lasting for years and decades may occur; these might be associated with El Niño

Static Equilibrium

there is essentially no change over time e.g. river flow generally stays the same for a period of days

Catchment

the area of land drained by a river and its tributaries

Condensation

the change from gas to liquid, such as when water vapour changes into water droplets

Convectional Rainfall

Often associated with intense thunderstorms, which occur widely in areas with ground heating such as the tropics and continental interiors

Cryosphere

areas of the Earth where water is frozen into snow or ice

Deforestation

The cutting down and removal of all or most trees in a forested area

Desalinisation

the process of converting saltwater to freshwater suitable for human consumption and industry

Desertification

Land degradation in arid, semi-arid and dry sub-humid regions resulting from various factors, including climatic variations and human activities

Dew Point

the temperature at which dew forms; it is a measure of atmospheric moisture

Out of the 3 states of water (solid, liquid, gas), which one is the most prevalent on Earth?

Gas/Vapour

Ice Shelf

a large floating platform of ice that forms where a glacier or ice sheet flows down to a coastline and onto the ocean surface

When does sea ice form?

when water in the oceans is cooled well below freezing

Ice Caps

thick layers of land-based ice that are smaller than 50,000km2

Alpine glaciers

thick masses of ice found in deep valleys and upland hollows

Permafrost

ground (soil or rock) that remains frozen for at least 2 consecutive years. Depths can vary from 1 to 1500 metres

Water table

the depth at which rock becomes completely saturated with water

Fossil Aquifers

the aquifers found in the deserts of Africa, Middle East and Australia

Saline Aquifers

when fossil aquifers are exploited unsustainably for irrigation, they become saline aquifers

Soil Water

water which is held together with air in the unsaturated upper layers of soil

Soil Moisture Budget

soils vary massively in their ability to store and transfer water

Soil Moisture

key in controlling the exchange of water and heat between the land surface and atmosphere through evapotranspiration

Surface Water

the free-flowing water of rivers, as well as the surface water stores of ponds and lakes

Are rivers a store or transfer of water?

Rivers act as both a store and a transfer of water

Are lakes a store or transfer of water?

Lakes are stores of fresh water

Wetlands

Areas of marsh, fen, peatland or water, which can be natural or artificial; permanent or temporary and static or flowing where is a dominance of vegetation

Factors that effect wetlands?

soils, topography, climate, hydrology, water chemistry, vegetation, human disturbance

Hadley Cell

The gap between the Equator and the tropics (Cancer and Capricorn)

Ferrel Cell

The gap between the tropics and the circles (Arctic and Antarctic)

Polar Cell

The gap between the circles and the Poles (North or South)

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

Orographic Rainfall

Air is forced to rise over hills and mountains

Frontal Rainfall

Air masses of different temperatures and densities meet, the warm air rising over the cool sinking air

Conventional Rainfall

Warm air rises from hot surfaces on a sunny day

Sublimation

meltwater evaporating and even ice directly produces steam

Drainage Basin System

the area of land drained by a river and its tributaries

Precipitation

May fall as rain, hail, sleet or snow. The duration and intensity will impact processes within the system

Evapotranspiration

Combined loss of water through evaporation and transpiration of plants

Run-off

The output of water from the drainage basin system as it moves across the land surface either as overland flow or channel flow

Interception store

Vegetation cover intercepts the precipitation and a store may be held on leaves and branches. Density of vegetation will affect this. Tropical rainforest can intercept 58% of rainfall

Surface Storage

This mainly occurs in built environments like puddles. In natural environments, infiltration normally occurs more quickly than rainfall or on impacted surfaces or bare rock

Soil Water Storage

Pore spaces between soil particles fill with air and water. The amount of pore spaces varies in different soils: clay 40-60% volume, sand 20-45%

Groundwater Store

Water stored underground in permeable and porous rocks

Channel Store

The volume of water in a river channel

Vegetation store

Vegetation cover intercepts the precipitation and a store may be held on leaves and branches. Density of vegetation will affect this. (Sometimes referred to as interception store)

Stemflow

Water flows down the stems of plants and trees