Physical Geography

Geography
Perihelion
The point of the earth’s orbit where the distance between the earth and sun is least. (~147 million km or 91.5 million mi) Occuring January when the sun is closest to earth.;
Aphelion
The point of the earth’s orbit where the distance between the earth is greatest. (~152 million km or 94.5 million mi) Occurs in July when its farthest.
Spring Equinox
March 20 or 21, when the subsolar point is located at the Equator
Summer Solstice
June 20 or 21, when the subsolar point is located at the Tropic of Cancer.
Fall Equinox
September 22 or 23, when the subsolar point is located at the Equator.
Winter Solstice
December 21 or 22, when the subsolar point is at the Tropic o Capricorn.
Wavelength
The distance between adjacent wave crests or wave troughs.
Wave amplitude
The overall height of any given wave as measured from the wave trough to the wave crest.
Electromagnetic spectrum
The radimt energy produced by the sun that is measured in progressive wavelengths.
Longwave
The portion of the electromagnetic spectrum that includes thermal infrared radiation.
Shortwave radiation
The portion of the electromagnetic spectrum that includes gamma rays, X-rays, ultra-violet radiation, visible light, and near-infrared radiation.
Insolation
Amount of solar radiation measured in watts per square meter (w/m2) that strikes a surface perpendicular to the Sun’s incoming rays.;
Radiation
Energy that is transmitted in the form of rays or waves.
Conduction
The transfer of heat energy from one substance to another by direct physical contact.
Convection
A circular cell of moving matter that contains warm material moving up and cooler matter moving down.
Ozone Layer
The layer of the atmosphere that contains high concentrations of ozone, which protect the earth from ultraviolet (UV) radiation.
Air pressure
The force that air molecules exert on a surface due to their weight.
Maritime vs. Continental effect
The difference in annual and daily tempreature that exists between coastal locations and those that are surrounded by large bodies of land.
Maritime
A place that is close to a large body of water that moderates temperature.
Continental
A place that is surrounded by a large body of land and that experiences a large annual range of temperature.
Urban Heat Island
The relatively warm temperatures associated with cities that occur because paved surfaces and urban structures absorb and release radiation differently than the surrounding countryside.
High-pressure system
A rotating column of air that descends toward the surface of the Earth where it diverges.
Low-pressure system
A rotating column of air where air converges at the surface and subsequently lifts.
cyclone
Low-pressure systems
anticyclone
high-pressure system
Advection
The horizontal transfer of air.
Pressure gradient force
The difference in barometric pressure that exists between adjacent zone of low and high pressure that results in air flow.
Coriolis Force
The force created by the earth’s rotation that causes winds to be deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.
Equatorial trough
Core of low pressure zone associated with Intertropical Convergence Zone.
Intertropical Convergence Zone (ITCZ)
Band of low pressure, calm winds, and clouds in tropical latitudes where air converges from the Southern and Northern Hemispheres.
Trade Winds
The primary wind system in the tropics that flows toward the ITCZ on the equatorial side of the Subtropical High-Pressure system. These winds flow to the southwest in the Northern Hemisphere and to the northwest in the Southern Hemisphere. 
Tropical Easterlies
Band of easterly winds that exists where Northern and Southern trade winds converge.
Monsoon
The seasonal change in wind direction that occurs in subtropical locations due to the migration of the ITCZ and the subtropical High-Pressure System.
Subtropical High Pressure System
Band of high air pressure, calm winds, and clear skies that exists at about 25 degrees to 30 degrees N and S latitude.
Sea Breeze
Daytime circulatory system along coasts where winds flow from a zone of high pressure over water to a zone of relatively low pressure over land.
Land Breeze
Nighttime circulatory system along coasts where winds from a zone of high pressure over land flow to a zone of relatively low pressure over water.
Valley Breeze
Upslope airflow that develops when mountain slopes heat up due to re-radiation and conduction over the course of the day.
Mountain Breeze
Downslope airflow that develops when mountain slopes cool off at night and relatively low pressure exists in valleys.
Chinook winds
Downslope airflow that results when a zone of high air pressure exists on one side of a mountain range and a zone of low pressure exists on the other.
Air Mass
A large body of air in the lower atmosphere that has distinct temperature and humidity characteristics.
Stationary Front
A boundary where contrasting air masses are flowing parallel to one another.
Downdraft
A rapidly moving current of cool air that flows downward in a thunderstrom.
Updrafts
An area of rapidly flowing air that is moving upward within a thunderstorm.
Albedo 
The ability to absorb heat. Water reflects sunlight, molecules spread and wind helps transfer heat.
Maximum Humidity 
How much water in the atmosphere.
Specific humidity
Exact humidity, water is in the air at that moment.
Relative humidity
The ratio between the specific and maximum humidity of a definable body of air.
Dew-point tempreature
The temperature at which condensation occurs in a definable body of air.
Adiabatic processes
Changes in temperature that occur due to variations in air pressure.
Dry Adiabatic lapse rate
The rate at which an unsaturated body of air cools while lifting or warms while descending. This rate is 10 degree celecius/1000m (5.5 degrees F/1000 ft).
Cirrus
Thin and whispy, high-level clouds; also known as mare’s tails.[image]
Cirrocumulus;
Appears as white patches; usually formed from Cirrus or Cirrostratus torn by winds; indicates approaching surface winds.[image]
Stratus
Thick, dull gray, low-lying layers; occurs as fog at ground level, often produces mist or drizzle.[image]
Nimbostratus (Nimbus)

dark rain clouds; form near the ground but usually extend upward.

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Warm Front
A frontal boundary where warm air is advancing into relatively cool air. This front is typically associated with slow, steady precipitation.;
Cold Front
A frontal boundary where cold air is advancing into relatively warm air. This front is typically associated with intense rain of short duration.;
Tropical Depression
A tropical low-pressure system with central sustained winds ranging between 20 knots and 34 knots (23 mph and 39 mph).
Tropical Storm
A tropical low-pressure system with maximum sustained winds between 35 knots and 63 knots (39 mph and 73 mph).
Hurricane
A tropical circulatory system with maximum sustained winds greater than 63 knots (73 mph).
Blizzard
Deadly winterstorms that are a combonation of blowing snow and wind resulting in very low visibilities. Accompanied also by heavy snowfall and serve cold temperature.
Saharan Air Layer
Is a mass of very dry, dusty air coming from Western and Northen Africa. Occurs late spring, summer and early fall where it moves 3-5 days across the tropical North Atlantic Ocean. It can cause significant negative impacts on tropical cyclone intensely forming.

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