 | Term | Definition |
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Geography |
the science that studies the relationships among natural systems, geographic areas, society, cultural activities, and the interdependence of all these systems over space |
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Physical geography |
the spatial analysis of all the physical elements and processes that make up the environment: energy, air, water, weather, climate, landforms, soils, animals, plants, microorganisms, and Earth itself |
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System |
any ordered, interrelated set of things and their attributes, linked by flows of energy and matter |
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Open flow system |
There are inputs and outputs of energy and/or matter |
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Closed Flow system |
There are no inputs or outputs of energy and/or matter, a cycle |
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Feedback |
a linkage between flow paths such that the flow in one pathway acts either to reduce or increase the flow in another pathway |
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Positive Feedback |
a process that results in an increase in one or more of the system's elements or attributes over time |
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Negative Feedback |
a process that acts to control the state of the system by dampening or reducing the system's elements or attributes over time |
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Equilibrium |
A steady state in which flow rates in the various pathways of a system remain about the same, thus the system remains balanced over time |
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Atmosphere |
Gaseous layers that surround the Earth, critical for the transport of heat and moisture |
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Hydrosphere |
Water portion of the Earth, including the cryosphere |
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Lithosphere |
Outermost solid layer of the Earth; its surface is sculpted into landforms eg. mountains and plains |
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Biosphere |
All living organisms of the Earth and the environment with which they interact |
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Geographic grid |
complete network of parallels and meridians on the surface of the globe that provides a system for locating places on the Earth's surface |
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Latitude |
Measure of how far North or South of the Equator a parallel is situated |
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Longitude |
Measure of how far east or west of the prime meridian a meridian is situated |
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Electromagnetic Radiation |
collection or spectrum of waves of a wide range of wavelengths travelling quickly away from the surface of an object |
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Wavelength |
the distance separating one wave crest from the next wave crest |
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Stefan-Bolzmann Law |
describes the relation of flow of energy emitted by a surface to its temperature |
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Wien's Law |
identifies the wavelength at which radiation emitted by a surface will be greatest given the temperature of the surface |
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Shortwave (solar) Radiation |
Energy emitted by the Sun |
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Insolation |
the flow of solar energy intercepted by an exposed surface (units are W/m2) |
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Revolution |
Earth's movement in orbit around the Sun |
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Rotation |
Earth turning on its axis |
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Circle of illumination |
circle that separates the day hemisphere (lit by the Sun) from the night hemisphere (not lit by the Sun) |
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Air |
Mixture of gases blended so thoroughly that it behaves as a single gas |
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Heterosphere |
outermost layer of the atmosphere where gases are layered by the atomic weight |
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Nitrogen |
largely a "filler" adding inert bulk to the atmosphere (gas in atmosphere) |
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Oxygen |
highly active chemically; combines readily with other substances (gas in atmosphere) |
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Argon |
inactive gas of little importance in natural process (gas in atmosphere) |
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Carbon Dioxide |
makes up 0.035% of the atmosphere; absorbs incoming shortwave radiation and outgoing longwave radiation (gas in atmosphere) |
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Water Vapour |
can vary highly in concentrations; good absorber of heat radiation, so it plays major role in warming of the lower atmosphere (gas in atmosphere) |
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Normal lapse rate |
6.4 degrees C/km |
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Air Density |
amount of gas molecules (mass) in a given volume |
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Air Pressure |
weight of the atmosphere above a given area |
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Air pollution |
is a chemical, particulate matter or biological agent that modifies the natural characteristics of the atmosphere |
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Transmission |
the passage of shortwave and longwave energy either through the atmosphere or water |
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Refraction |
the 'bending' of insolation as it passes from one medium to another (ie from space to atmosphere to water) |
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reflection |
energy redirected into space without being absorbed |
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albedo |
proportion of shortwave radiant energy that is reflected upward by a surface |
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Absorption |
the assimilation of radiation by molecules of matter and its conversion from one form of energy to another |
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Latent heat |
heat that is taken up and stored in the form of molecular motion when a substance changes state from a solid to liquid, from a liquid to gas, or from a solid directly to gas |
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Latent Heat transfer |
flow of latent heat during a change of state |
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sensible heat |
quantity of heat held by an object that can be sensed by touching or feeling |
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conduction |
flow of heat from one substance to another by direct, molecule - molecule contact |
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convection |
physical mixing of gases or liquids with a strong vertical motion |
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advection |
physical mixing of gases or liquids with a strong horizontal motion |
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Net Radiation (Q*) |
the difference between all incoming radiation and all outgoing radiation |
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Energy Surplus |
Place where radiant energy flows in faster than it flows out, net radiation is positive |
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Energy Deficit |
Place where radiant energy flows out faster than it flows in, net radiation is negative |
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Weight |
The acceleration of mass by gravity creates this force |
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Atmospheric Pressure |
is the force produced by the weight of a column of air above a unit area of surface |
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Barometer |
measures atmospheric pressure |
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Wind |
horizontal movement of air across Earth's surface |
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Gravity |
Equally compresses the atmosphere world wide (forces that determine wind) |
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Pressure Gradient |
pushes the parcel towards low pressure (forces that determine wind) |
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Coriolis Force |
always acts at right angles to the direction of motion (forces that determine wind) |
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Friction |
this force is proportional to the wind speed and always acts in the direction opposite to the direction of motion |
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Convection loop |
caused by differential heating and cooling of the Earth's surface |
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Sea Breeze |
afternoon wind that brings cool air off the water towards the land |
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land breeze |
nighttime wind that brings cooler air, chilled over land by nighttime radiant cooling towards the water |
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Deflection |
to the right in the Northern Hemisphere, and to the left in the Southern hemisphere |
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Equatorial Low Pressure Trough |
large amounts of insolation warms air at the equator which rises and produces a zone of low pressure |
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Intertropical Convergence Zone (ITCZ) |
Zone of light winds where air meets and rises |
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Hadley cell |
air rises over the equator is drawn poleward by the pressure gradient, and descends at about 30 degrees latitude to complete a convection loop |
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Subtropical high-pressure cell |
As air descends in each Hadley cell, at about 30 degrees latitude, it is heated by compression and creates this cell |
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Subpolar low-pressure cell |
Warm and cold pressure meet and it characterised by dominantly upwards motion of warm air and downwards motion of cold air (type of cell) |
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Polar High-Pressure cell |
Cold air descends causing this cell |
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Geostrophic wind |
occurs at upper levels of the atmosphere and runs parallel to the isobars |
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Rossby waves |
Horizontal undulations (the isobars are not straight lines, they are wavy) in the flow path of the upper air westerlies |
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Jet Streams |
high-speed air flows in narrow zones of upper air circulation |
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Ocean currents |
Any persistent, dominantly horizontal flow of ocean water |
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Surface Currents |
driven by prevailing winds (Ocean Currents) |
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Deep Currents |
Powered by changes in temperature and density occuring in surface water that cause them to sink |
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Gyres |
Track the movements of air around the subtropical high pressure cells |
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Eustatic Change |
change related to the water volume in the oceans |
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Hydrologic Cycle |
movement of water among the great global reservoirs |
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Humidity |
the amount of water vapor present in the air |
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Specific Humidity |
the actual quantity of water vapor held by a parcel of air (g/kg) |
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relative humidity |
compares the amount of water vapour present to the maximum amount that the air can hold at that temperature expressed as a percentage |
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Dew Point temperature |
temperature of an air mass at which the air holds its full capacity of water vapour |
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Stability |
refers to the tendency of an air parcel (including its water vapour) to either remain in place or to change vertical position by either ascending or descending |
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Adiabatic Process |
a change of temperature within a gas that occurs solely as a result of a pressure change |
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Moist (wet) adiabatic lapse rate |
rate at which a rising air parcel is cooled by expansion when condensation is occuring (4-10 degrees C/1000m ) |
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Cloud |
made up of water droplets or ice particles suspended in air |
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Stratiform |
flat, blanket-like clouds that cover large areas |
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Cumuliform |
Puffy, globular clouds |
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Cirroform |
Whispy clouds made of ice crystals |
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Planetesimal hypothesis |
The Earth formed from a large, slowly rotating nebula according to this theory |
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Perihelion |
Earth is closest to the sun (Jan 3) |
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Aphelion |
Earth is farthest from the sun (July 4) |
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Plane of the ecliptic |
plane touching all points of the Earth's orbit |
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Solar Wind |
Electromagnetically charged particles emitted by the Sun |
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Seasonality |
caused by sun's altitude, sun's declination and day length during the year |
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Altitude |
Sun's position above the horizon |
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Declination |
latitude of the sub-solar point |
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Subsolar point |
place on the Earth that receives the highest concerntration of the Sun's rays |
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Summer Solstice |
larger part of Northern hemisphere is in daylight, so day is longer than night |
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Winter Solstice |
smaller part of the Northern Hemisphere is in daylight, so day is shorter than night |
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homosphere |
gases are blended into "air" |
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Temperature Inversion |
When the normal lapse rate begins to increase at some altitude. |
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scattering |
redirection of electromagnetic radiation without changing its wavelength |
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Jet condensation trails (contrails) |
produce high cirrus clouds that cause cooler days and warmer nights |
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greenhouse effect |
the mechanism by which the atmosphere traps longwave radiation and returns it to the surface |
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global energy budget |
a full account of all the important energy flows among the sun, atmosphere, surface and space forms |
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urban heat island |
certain factors create a microclimate around each city |
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updraft |
air motions that are dominantly vertically (up) |
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downdraft |
air motions that are dominantly vertically (down) |
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polar front |
waves arise in a zone of contact between cold polar air and warm tropical air |
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Poleward heat transport |
rossby waves are a primary mechanism for _________ when it brings warm air poleward and cold air equatorward |
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equatorial currents |
moves warm water westwards and then poleward along the east coasts of continents |
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thermohaline circulation |
describes the global circulation of the oceans |
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temperature |
a measure of the kinetic energy of individual molecules |
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Heat |
energy transfer that occurs between two systems of different temperature |
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surface temperature |
is determined by the balance among various energy flows that move across it |
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Day |
incoming radiation normally exceeds outgoing radiation |
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Night |
outgoing radiation normally exceeds incoming radiation |
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Air temperature |
temperature observed at 1.2m above the ground surface |
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Isotherms |
lines drawn to connect locations having the same temperature |
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glacio-eustatic factors |
influenced by the volume of water stored in glaciers and ice sheets |
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saturation |
at this temperature the air holds the maximum amount of water vapour possible and if futher cooling occurs, condensation will begin |
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stable |
an air parcel is ________ if it resists vertical movements, or returns to its starting place if disturbed |
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unstable |
an air parcel is ________ if it continues to rise until it reaches and altitude of air of similar density |
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uplifted |
when an air parcel is ________ atmospheric pressure on the parcel lowers and the parcel will expand and cool |
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descends |
when an air parcel __________, atmospheric pressure on the parcel increases and the parcel will compress and warm |
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dry adiabatic lapse rate |
rate at which a rising air parcel is cooled by expansion when no condensation is occuring (1 degree C / 100 m) |
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lifting condensation level |
the level in the atmosphere where a rising air parcel is cooled to its dew point temperature and condensation occurs |
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supercooled |
water droplets which remain below freezing in a liquid state |
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condensation nucleus |
a tiny center of solid matter around which each cloud particle is formed (salt, dust, soot, ash) |
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orographic |
air moving up and over a mountain barrier (causes of precipitation) |
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Convectional |
unequal heating at the ground surface (causes of precipitation) |
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frontal |
when a mass of cooler, denser air slides under a mass of warmer lighter air, and the warmer air is lifted aloft (causes of precipitation) |
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Thunderstorm |
intense local storm associated with a tall dense cumulonimbus cloud in which there are very strong updrafts of air |
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fog |
a cloud layer on the ground, formed when the air and dew point temperatures are nearly identical |
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advection |
formed when air migrates to a place where conditions allow saturation to occur (type of fog) |
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radiation |
forms when a surface cools the air directly above (type of fog) |
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rime |
consists of tiny supercooled droplets that turn into frost (type of fog) |
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ice-crystal |
forms at extremely low temperatures by sublimation (type of fog) |
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air mass |
a large body of air with fairly uniform temperature and moisture characteristics |
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weather system |
recurring patterns of atmospheric circulation associated with characteristic weather |
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cold front |
cold air mass lifts a warm air mass aloft, often forming a line of clouds and thunderstorms |
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front |
a given air mass usually has a sharply defined boundary between itself and a neighbouring air mass. |
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frontal precipitation |
precipitation occuring along the boundaries of a different air masses |
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warm front |
warm air advancing towards cold air and rides up and over the cold air, causing stratus cloud formation and precipitation |
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occluded front |
a warm front is abruptly overtaken by a cold front leading to precipitation |
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cyclogenesis |
two anticyclones one with warm subtropical air and the other with cold polar air |
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easterly wave |
slowly moving trough of low pressure within the belt of tropical easterlies (5 degree - 30 degree N and S over ocean) |
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tornado |
a small and intense cyclonic vortex in which air spiral at great speed |
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