Glossary of Terms: F

Facilitation

Modification of a system that makes subsequent modifications easier.

 

Facilitation Model of Succession

This model of succession suggests that the change in plant species dominance over time is caused by modifications in the abiotic environment that are imposed by the developing community. Thus the entry and growth of the later species depends on earlier species preparing the ground.

 

Fahrenheit Scale

Scale for measuring temperature. In this scale, water boils at 212° and freezes at 32°.

 

Fall

Season between summer and winter. Astronomically it is the period from the autumnal equinox to the winter solstice in the Northern Hemisphere.

 

False Origin

Location of the starting coordinates picked to the south and west of the true origin of a rectangular coordinate system. False origins are used to avoid negative coordinates.

 

Falsification

Falsification is a procedure used in science to test the validity of a hypothesis or theory. It involves stating some output from theory in specific and finding contrary cases among experiments or observations.

 

Fault

A fracture in rock caused by stress.

 

Fault Plane

The plane that represents the fracture surface of a fault.

 

Fault Scarp

The section of the fault plane exposed in a fault. Also called an escarpment.

 

Feedback Loop

Process where the output of a system causes positive or negative changes to some measured component of the system.

 

Feldspar

A group of common aluminum silicate minerals that contains potassium, sodium, or calcium.

 

Felsic Magma

Magma that is relatively rich in silica, sodium, aluminum, and potassium. This type of magma solidifies to form rocks relatively rich in silica, sodium, aluminum, and potassium.

 

Fen

A habitat composed of woodland and swamp.

 

Fermentation

Decomposition and breakdown of organic matter by anaerobic means.

 

Fern

A group of about 11,000 species of vascular seedless plants that belong to the division Pterophyta. About 75 percent of the various species of ferns are found in the tropics. Some ferns grow on the branches of trees as epiphytes.

 

Ferrel Cell

Three-dimensional atmospheric circulation cell located at roughly 30 to 60° North and South of the equator.

 

Ferricretes

Sedimentary rock created by the chemical precipitation of iron.

 

Fertilizer

Substance that adds inorganic or organic nutrients to soil for the purpose of increasing the growth of crops, trees, or other vegetation.

 

Fetch

The distance of open water in one direction across a body of water over which wind can blow.

 

Field Capacity

The water remaining in a soil after the complete draining of the soil's gravitational water.

 

Firn

Névé on a glacier that survives the year's ablation season. With time much of the firn is transformed into glacial ice.

 

Firn Limit

The lower boundary of the zone of accumulation on a glacier where snow accumulates on an annual basis. Also called the Firn Line.

 

Firn Line

See firn limit.

 

First Law of Thermodynamics

See Law of Conservation of Energy.

 

Fish

Group of vertebrate animals that inhabit aquatic habitats.

 

Fission (Nuclear)

Process where the mass of an atomic nucleus is made smaller by the removal of subatomic particles. This process releases atomic energy in the form of heat and electromagnetic radiation.

 

Fissionable Isotope

Isotope that can undergo nuclear fission when hit by a neutron at the right speed. Examples include uranium-235 and plutonium-239.

 

Fissure

Opening or crack in the Earth's crust.

 

Fitness

A measure of the health of a species in terms of physiology and future reproductive success.

 

Fixed Energy

A process, like photosynthesis, where organisms repackage inorganic energy into organic energy.

 

Fjord

A glacial valley or glacial trough found along the coast that is now filled with a mixture of fresh water and seawater.

 

Flash Flood

A rapid and short-lived increase in the amount of runoff water entering a stream resulting in a flood.

 

Flocculation

Chemical processes where salt causes the aggregation of minute clay particles into larger masses that are too heavy to remain suspended water.

 

Flood

Inundation of a land surface that is not normally submerged by water from quick change in the level of a water body like a lake, stream, or ocean.

 

Flood Basalt

See plateau basalt.

 

Floodplain

Relatively flat area found alongside the stream channel that is prone to flooding and receives alluvium deposits from these inundation events.

 

Flood Tide

Time during the tidal period when the tide is rising. Compare with ebb tide.

 

Fluid

Substance, gas or liquid, that has the property of flow.

 

Fluid Drag

Reduction in the flow velocity of a fluid by the frictional effects of a surface.

 

Fluvial

Involving running water. Usually pertaining to stream processes.

 

Focus

See earthquake focus.

 

Föhn Wind

European equivalent of chinook wind.

 

Fog

Fog exists if the atmospheric visibility near the Earth's surface is reduced to 1 kilometer or less. Fog can be composed of water droplets, ice crystals or smoke particles. Fogs composed primarily of water droplets are classified according to the process that causes the air to cool to saturation. Common types of this type of fog include: radiation fog; upslope fog; advection fog; evaporation fog; ice fog; and frontal fog.

 

Fold

Wavelike layers in rock strata that are the result of compression.

 

Folding

The deformation of rock layers because of compressive forces to form folds.

 

Foliar Leaching

Process in which water from precipitation removes plant nutrients from the surface of leaves.

 

Foliation

Process where once randomly distributed platy minerals in a rock become reoriented, because of metamorphism, in a parallel manner.

 

Food Chain

Movement of energy through the trophic levels of organisms. In most ecosystems, this process begins with photosynthetic autotrophs (plants) and ends with carnivores and detritivores.

 

Food Web

A model describing the organisms found in a food chain. Food webs describe the complex patterns of energy flow in an ecosystem by modeling who consumes who.

 

Foot Wall

The bottommost surface of an inclined fault.

 

Force

Process that changes the state of rest or motion of a body.

 

Force of Acceleration

Force resulting in the speed of a moving body to increase.

 

Forest

Ecosystem dominated by trees. Major forest biomes include tropical evergreen forest, tropical savanna, deciduous forest, and boreal forest.

 

Forminifera

Microscopic organisms of the group protozoa that are found living mainly in marine environments. These organisms produce shells rich in calcium carbonate. Sedimentation and lithification of these shells produces the sedimentary rock chalk.

 

Foreset Bed

Deltaic deposit of alluvial sediment that is angled 5 to 25° from horizontal. Most of the delta is made up of these deposits.

 

Foreshock

Small earth tremors that occur seconds to weeks before a significant earthquake event.

 

Fossil

Geologically preserved remains of an organism that lived in the past.

 

Fossil Fuel

Carbon based remains of organic matter that has been geologically transformed into coal, oil and natural gas. Combustion of these substances releases large amounts of energy. Currently, humans are using fossil fuels to supply much of their energy needs.

 

Freezing

The change in state of matter from liquid to solid that occurs with cooling. Usually used in meteorology when discussing the formation of ice from liquid water.

 

Freezing Rain

A type of precipitation. Occurs when liquid rain hits a cold surface and then immediately freezes into ice. For this to occur, a surface temperature inversion is usually required. In such an inversion, the surface must have a temperature below freezing, while the temperature of the atmosphere where the precipitation forms is above freezing.

 

Freeze-Thaw Action

Processes associated with daily and seasonal cycles of freezing and melting.

 

Freons

See chlorofluorocarbons.

 

Fresh Water

Water that is relatively free of salts.

 

Friction

Resistance between the contact surfaces of two bodies in motion.

 

Frictional Force

Force acting on wind near the Earth's surface due to frictional roughness. Causes the deceleration of wind.

 

Front

Transition zone between air masses with different weather characteristics.

 

Frontal Fog

Is a type of fog that is associated with weather fronts, particularly warm fronts. This type of fog develops when frontal precipitation falling into the colder air ahead of the warm front causes the air to become saturated through evaporation.

 

Frontal Lifting

Lifting of a warmer or less dense air mass by a colder or more dense air mass at a frontal transitional zone.

 

Frontal Precipitation

See convergence precipitation.

 

Frost

Deposition of ice at the Earth's surface because of atmospheric cooling.

 

Frost Creep

Slow mass movement of soil downslope that is initiated by freeze-thaw action. Occurs where the stresses on the slope material are too small to create a rapid failure.

 

Frost Point

Is the temperature at which water vapor saturates from an air mass into solid usually forming snow or frost. Frost point normally occurs when a mass of air has a relative humidity of 100%.

 

Frost Wedging

A process of physical weathering in which water freezes in a crack and exerts force on the rock causing further rupture.

 

Fujita Tornado Intensity Scale

Tornado classification system developed by T. Theodore Fujita. This system six levels from F0 to F5. These levels are based on the estimated speed of the tornado's winds from proxy information like property damage.

 

Fundamental Niche

Describes the total range of environmental conditions that are suitable for a species existence without the effects of interspecific competition and predation from other species.

 

Fungi

Group, at the kingdom level, in the classification of life. Multicellular organisms that have a eukaryotic cell type, mitochondria, and a cell wall composed of chitin and other noncellulose polysaccharides.

 

Funnel Cloud

A tornado which is beginning its descent from the base of a cumulonimbus cloud. This severe weather event may or may not reach the ground surface.

 

Fusion (Nuclear)

Process where the mass of an atomic nucleus is made larger by the addition of subatomic particles. This process releases atomic energy in the form of heat and electromagnetic radiation.

 

 

Citation: Pidwirny, M. (2006). "Glossary of Terms: F". Fundamentals of Physical Geography, 2nd Edition. Date Viewed. http://www.physicalgeography.net/physgeoglos/f.html