A Level Geography ~ Key Definitions

the lowest region of the atmosphere, extending from the earth's surface to a height of about 6–10 km

the interface between the troposphere and the stratosphere.

the layer of the earth's atmosphere above the troposphere, extending to about 50 km above the earth's surface

balance sheet of energy income against expenditure

vaporization of a liquid that occurs from the surface of a liquid into a gaseous phase that is not saturated with the evaporating substance.

the change of the physical state of matter from gas phase into liquid phase, and is the reverse of vaporization

the proportion of the incident light or radiation that is reflected by a surface

the throwing back by a body or surface of light or heat without absorbing it.

the process in which light and heat are deflected or diffused.

the transfer of internal energy within a body due to a temperature gradient

the transfer of heat from one place to another by the movement of fluids.

the energy radiating from the Earth as infrared radiation at low energy to Space.

radiant energy with wavelengths in the visible, near-ultraviolet, and near-infrared spectra.

the flux of heat from the Earth's surface to the atmosphere that is associated with evaporation of water at the surface and subsequent condensation of water vapor in the troposphere

the process where heat energy is transferred from the Earth's surface to the atmosphere by conduction and convection

a large-scale atmospheric convection cell in which air rises at the equator and sinks at medium latitudes, typically about 30° north or south.

the average motion of air in the mid-latitudes - sinking air near 30 deg and rising air farther poleward

the large-scale movement of air, and the means by which thermal energy is distributed on the surface of the Earth.

A belt of low pressure which circles the Earth near the equator where the trade winds of the Northern and Southern Hemispheres come together.

a condition of the atmosphere in which the pressure is above average

a condition of the atmosphere in which the pressure is below average

a mass moving in a rotating system experiences a force acting perpendicular to the direction of motion and to the axis of rotation.

the force which results when there is a difference in pressure across a surface.

the balance between the Coriolis force and the horizontal pressure force in the atmosphere which produces a wind parallel to the isobars. (Simplified)

Coriolis forces deflect winds and freely moving objects to the right in the northern hemisphere and to the left in the southern hemisphere.

a wind blowing steadily towards the equator from the north-east in the northern hemisphere or the south-east in the southern hemisphere

an equatorial region of the Atlantic Ocean with calms, sudden storms, and light unpredictable winds.

the boundary between the polar cell and the Ferrel cell in each hemisphere, where the polar front arises as a result of cold polar air meeting warm tropical air.

a narrow variable band of very strong predominantly westerly air currents encircling the globe several miles above the earth

are giant meanders in high-altitude winds with major influence on weather.

winds at the top of the troposphere which are generally blow towards the poles and are westerly in direction. (Simplified)

a warm dry southerly wind developing in the lee of any mountain range.

produced when moist air is lifted as it moves over a mountain range

a region having little rainfall because it is sheltered from prevailing rain-bearing winds by a range of hills.

downslope winds flowing from high elevations of mountains and hills down their slopes to the valleys below.

a warm wind which blows up a steep slope or mountain side, driven by heating of the slope through insolation

water in the gaseous state in the atmosphere often at a temperature below the boiling point. (Simplified)

quantity representing the amount of water vapour in the atmosphere or in a gas

the transition of a substance directly from the solid to the gas phase without passing through an intermediate liquid phase

where any particles settle onto a surface. (Simplified)

the process of reducing heat through a change in air pressure caused by volume expansion

the rate at which atmospheric temperature decreases with increasing altitude in conditions of thermal equilibrium.

The rate of decrease of atmospheric temperature with increase in altitude

the temperature at which the air can no longer "hold" all of the water vapor which is mixed with it, and some of the water vapor must condense into liquid water

The height at which air reaches saturation - usually forming the base of a cloud. (Simplified)

the rate of temperature decrease with altitude for a parcel of dry or unsaturated air rising under adiabatic conditions

the rate at which the temperature of a parcel of air saturated with water vapour changes as the parcel ascends or descends.

the point at which air will neither rise or fall. (Simplified)

a condition where the atmosphere is likely to change and a high degree of variability is possible. (Simplified)

Stable unsaturated air that will result in instability in the event or on the condition that the air becomes saturated

Tiny particles of matter that have a special chemical affinity for water molecules, so that condensation may take place on these nuclei at relative humidities under 100 percent.

The absence of fronts means winds may be very light. Consequently, high-pressure areas are often associated with settled, dry and bright conditions

a greyish-white crystalline deposit of frozen water vapour formed in clear still weather on vegetation, fences, etc.

frost formed on cold objects by the rapid freezing of water vapour in cloud or fog.

tiny drops of water that form on cool surfaces at night, when atmospheric vapour condenses.

the fog that arises from the movement of humid air over a surface that is already cool

the condensed moisture of the atmosphere falling visibly in separate drops.

pellets of frozen rain which fall in showers from cumulonimbus clouds.

water vapour frozen into ice crystals and falling in light white flakes or lying on the ground as a white layer.

a visible mass of condensed watery vapour floating in the atmosphere, typically high above the general level of the ground.

a reversal of the normal decrease of air temperature with altitude, or of water temperature with depth.

the trapping of the sun's warmth in a planet's lower atmosphere, due to the greater transparency of the atmosphere to visible radiation from the sun than to infrared radiation emitted from the planet's surface.

a gas that contributes to the greenhouse effect by absorbing infrared radiation.

Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years

the movement of warm water on the surface towards the North Pole and cold water at depth, south and then around the world. (Simplified)

an irregularly occurring and complex series of climatic changes affecting the Pacific region

the heat required to raise the temperature of I kg of a given substance by 1 degree

a metropolitan area that is significantly warmer than its surrounding rural areas due to human activities.