Thursday, November 23rd, 2017

* E=mc2 -Einstein's famous theory of relativity formula known as the energy-mass relation. The energy e is equal to the mass m multiplied by the speed of light squared c2. A small mass produces an enormous amount of energy.
* Earthflow-A flowing mass of fine grained soil particles mixed with water. Earthflows are less fluid than mudflows.
* Earthlight (Earthshine) - The faint illumination of the dark part of the moon's disk produced by sunlight reflected onto the moon from the earth's surface and atmosphere.
* Earthquake- the shaking of Earth's crust caused by a sudden release of energy.
* Earthquake-A sudden motion or trembling of the Earth caused by the abrupt release of slowly accumulated elastic energy in rocks.
* Eccentric -Noncircular; elliptical (applied to an orbit).
* Eccentricity -A value that defines the shape of an ellipse or planetary orbit; the ratio of the distance between the foci and the major axis.
* Eccentricity-The shape of the ellipse that constitutes the Earth's orbit around the Sun.
* Echo sounder-An instrument that emits sound waves and then records them after they reflects off the sea floor. The data is then used to record the topography of the sea floor.
* Eclipse -The cutting off of light from one celestial body by another.
* Eclipse-A phenomenon that occurs when a heavenly body is shadowed by another and therefore rendered invisible. When the Moon lies directly between the Earth and the Sun, the Moon blocks our view of the Sun and we observe a solar eclipse. When the Earth lies directly between the Sun and the Moon, the Earth's shadow falls on the Moon and we observe a lunar eclipse.
* Ecliptic -The plane of Earth's orbit about the Sun. The sun's apparent path across the sky that tracks a circle through the celestial sphere.
* Effluent stream-A stream that receives water from groundwater because its channel lies below the water table. (syn: gaining stream)
* El Nino (NiƱo, Nin~o)- The cyclical warming of East Pacific Ocean sea water temperatures off the western coast of South America that can result in significant changes in weather patterns in the United States and elsewhere. This occurs when warm equatorial waters move in and displace the colder waters of the Peru Current, cutting off the upwelling process.
* Elastic deformation-A deformation such that if the stress is removed, the material springs back to its original size and shape.
* Elastic limit-The maximum stress that an object can withstand without permanent deformation.
* Electromagnetic energy- forms of energy that travel at the speed of light (300,000km/sec), each form having a different wavelength (and frequency).
* Electromagnetic radiation-The transfer of energy by an oscillating electric and magnetic field; it travels as a wave and also behaves as a stream of particles.
* Electromagnetic spectrum- total range of electromagnetic waves, from radio waves to gamma waves.
* Electromagnetic spectrum-The entire range of electromagnetic radiation from very long wavelength (low frequency) radiation to very short wavelength (high frequency) radiation.
* Electron-A fundamental particle which forms a diffuse cloud of negative charge around an atom.
* Element-A substance that cannot be broken down into other substances by ordinary chemical means. An element is made up of the same kind of atoms.
* Ellipse -A closed curve that is formed from two foci or points in which the sum of the distances from any point on the curve to the two foci is a constant. Johannes Kepler first discovered that the orbits of the planets are ellipses, not circles; he based his discovery on the careful observations of Tycho Brahe.
* Elliptical galaxy-A galaxy with an elliptical appearance.
* Emergent coastline-A coastline that was recently under water but has been exposed either because the land has risen or sea level has fallen.
* Emission nebula-A glowing cloud of interstellar gas.
* Emission spectrum-See "spectrum."
* End moraine-A moraine that forms at the end, or terminus of a glacier.
* Energy resources-Geologic resources, including petroleum, coal, natural gas, and nuclear fuels, used for heat, light, work, and communication.
* Energy- Usable heat or power; in physics, it is the capacity of a physical system to perform work.
* Eon-The longest unit of geologic time. The most recent eon, the Phanerozoic Eon, is further subdivided into eras.
* Epicenter- the point on Earth's surface directly above the focus of an earthquake.
* Epicenter-The point on the Earth's surface directly above the focus of an earthquake.
* Epicycle- a small orbit along which a planet traveled in Ptolemy's geocentric model of the solar system. They were created to explain retrograde motion. They are not real. This model is wrong.
* Epidemiology-The study of the distribution of sickness in a population.
* Epoch- a subdivision of a geological period on the geologic timetable.
* Epoch-The smallest unit of geologic time. Periods are divided into epochs.
* Equinox- The date when the sun is directly overhead at noon on the equator, occurring on or around both March 21 and September 22, the former is the vernal (spring) equinox and the latter the autumnal (fall) equinox in the Northern Hemisphere and the reverse on the Southern Hemisphere. On the date of the equinox (literally, meaning "equal nights") nights are of equal length all across the globe from pole to pole. There are 12 hours of daylight and 12 hours of darkness on these dates.
* Equinox-Either of two times during a year when the Sun shines directly overhead at the Equator. The equinoxes are the beginnings of spring and fall, when every portion of the Earth receives 12 hours of daylight and 12 hours of darkness.
* Era- a major division of geologic time.
* Era-A geologic time unit. Eons are divided into eras and in turn eras are subdivided into periods.
* Erosion- The movement of weathered material downslope under the influence of gravity. Water acts as a catalyst and as a lubricant. Some common types of erosion includes landslides, rockfalls, creep, etc. Erosion takes weathered material and puts it in a river so it can be transported to the beach. Moving water, wind, and ice (glaciers) are agents of erosion.
* Erosion-The removal of weathered rocks by moving water, wind, ice, or gravity.
* Erratic (glacial)- Large rocks or other debris deposited by a glacier, usually in an area far removed from its source. Commonly used to indicate a big chunk of debris which is clearly out of place and shouldn't even be where it is. Eruption- The process by which solid, liquid, and gaseous materials are ejected into the earth's atmosphere and onto the earth's surface by volcanic activity. Eruptions range from the quiet overflow of liquid rock to the tremendously violent expulsion of pyroclastics.
* Erratic-A boulder that was transported to its present location by a glacier. Usually different from the bedrock in its immediate vicinity.
* Eruption Cloud- The column of gases, ash, and larger rock fragments rising from a crater or other vent. If it is of sufficient volume and velocity, this gaseous column may reach many miles into the stratosphere, where high winds will carry it long distances.
* Eruption- The process by which solid, liquid, and gaseous materials are ejected into the earth's atmosphere and onto the earth's surface by volcanic activity. Eruptions range from the quiet overflow of liquid rock to the tremendously violent expulsion of pyroclastics.
* Eruptive Vent- The opening through which volcanic material is emitted.
* Esker- a long, winding ridge formed when sand and gravel fill meltwater tunnels beneath a glacier.
* Esker-A long snake-like ridge formed by deposition in a stream that flowed on, within, or beneath a glacier.
* Estuary-A bay that formed when a broad river valley was submerged by rising sea level or a sinking coast.
* Eutrophic lake-A lake characterized by abundant dissolved nitrates, phosphates, and other plant nutrients and by a seasonal deficiency of oxygen in bottom water. Such lakes are commonly shallow.
* Evacuate- Temporarily move people away from possible danger.
* Evaporation fog-Fog that forms when air is cooled by evaporation from a body of water, commonly a lake or river. The water evaporates, but the vapor cools and condenses to fog.
* Evaporation- The change of state of water from the liquid to vapor phase. Requires the addition of 80 calories per cubic centimeter.
* Evaporation-The transformation of a liquid to a gas.
* Evaporite deposit-A chemically precipitated sedimentary rock that formed when dissolved ions were concentrated by evaporation of water.
* Evapotranspiration- Water used by plants and animals and subsequently returned directly to the atmosphere.
* Evolution- The theory that living organisms mutate and change, generally from simple to increasingly complex forms.
* Evolution-The change in the physical and genetic characteristics of a species over time.
* Exfoliation- the peeling of surface layers from exposed bedrock.
* Exfoliation-Fracturing in which concentric plates or shells split from the main rock mass like the layers of an onion.
* Explosive eruption -A dramatic volcanic eruption which throws debris high into the air for hundreds of miles. The lava is low in silicate and can be very dangerous for people near by. An example is Mount St. Helens in 1980.
* Extensional stress-Tectonic stress in which rocks are pulled apart.
* Externalities-The cost of living in a degraded environment, including direct costs such as medical bills, lost work, and damage to waterways, crops, and livestock. It also includes indirect costs of environmental degradation such as reduction in tourism and lowered land values.
* Extinct Volcano- A volcano that is not presently erupting and is not likely to do so for a very long time in the future.
* Extrusion- The emission of magmatic material at the earth's surface. Also, the structure or form produced by the process (e.g., a lava flow, volcanic dome, or certain pyroclastic rocks).
* Extrusive igneous rock-An igneous rock formed from material that has erupted onto the surface of the Earth.
* Extrusive rock (volcanic) - igneous rock that forms from quickly cooling lava, above Earth's surface.
* Eye (of a storm)- calm, clear center of a tropical low (hurricane).

* Fall-A type of mass wasting in which unconsolidated material falls freely or bounces down the face of a cliff.
* Fault- A crack or fracture in the earth's crust in which there has been movement of one or both sides relative to the other. Movement along the fault can cause earthquakes or, in the process of mountain-building, can release underlying magma and permit it to rise to the surface as a volcanic eruption.
* Fault creep-A continuous, slow movement of solid rock along a fault resulting from a constant stress acting over a long time.
* Fault zone-An area of numerous closely spaced faults.
* Fault-A fracture in rock along which displacement has occurred.
* Faunal succession (principle of)-See "principle of faunal succession."
* Feedback mechanism-A feedback mechanism occurs when a small initial perturbation affects another component of the Earth systems, which amplifies the original effect, which perturbs the system even more, which leads to an even greater effect, and so on.
* Feldspar-A common group of aluminum silicate rock-forming minerals that contain potassium, sodium, or calcium.
* Felsic- A high silica igneous rock having abundant light-colored minerals.
* Felsic-A term describing any light-colored igneous rock containing large amounts of feldspar and silica.
* Fetch- The distance over which a wind of nearly constant direction has blown, usually over a consistent surface such as water or a forest or a field. Most often the fetch is applied to a distance over water and used to determine the height of wind-generated waves. However, fetch can be applied to many studies of energy and water vapor transfers from the surface to the air. For example, the intensity of lake-effect snow depends in part on the distance the wind blows over open water.
* Fetch-The distance that the wind has travelled over the ocean without interruption.
* Field value- The property that is being measured at a location, such as elevation, temperature and pressure.
* Fiord-A long, deep, narrow arm of the sea bounded by steep walls, generally formed by submergence of a glacially eroded valley.
* Firn-Hard, dense snow that has survived through one summer melt season. Firn is transitional between snow and glacial ice.
* Fissility-Fine layering along which a rock splits easily.
* Fissure-An extensive break, crack, or fracture in rocks. Fissure eruptions are usually gentle volcanic eruptions in which lava flows from fissures in the Earth's crust.
* Flare -A sudden eruption of energy on the solar disk lasting minutes to hours, from which radiation and particles are emitted.
* Flash Flood- A flood caused by heavy or excessive rainfall in a short period of time, generally less than 6 hours. A flash flood rises rapidly, often with little or no warning.
* Flash flood-A rapid, intense, local flood of short duration.
* Flood basalt-Basaltic lava that erupts gently in great volume from cracks at the Earth's surface to cover large areas of land and form basalt plateaus.
* Flood plain-That portion of a river valley adjacent to the channel; it is built by sediment deposited during floods and is covered by water during a flood.
* Flood-Any relatively high stream flow that overtops the stream banks in any part of its course, covering land that is not usually under water.
* Floodplain- The low relief lands bordering a stream or river, common to the mature and old age stages of stream development. Floodplains store excess water in times of high water, and excess sediments in times of low water. Beware of building your dream house on a floodplain - they tend to get rather wet at irregular intervals.
* Flow-Mass wasting in which individual particles move downslope as a semifluid not as a consolidated mass.
* Flurries- Popular term for a usually light and brief snow shower. Accumulations of snow are very light, such as a dusting, or none at all.
* Fluvial- Produced by the action of of flowing water.
* Fly ash-Minerals that escape into the atmosphere, usually when coal burns and eventually settles as gritty dust.
* Focus- a point within Earth where an earthquake originates.
* Focus-The initial rupture point of an earthquake.
* Foehn Winds- Winds descending downslope from mountains which are characteristically warm and dry due to adiabatic compression. The term originally referred to such winds flowing down the Alpine valleys of Germany and Austria but is now used as the generic term for such airflows. The Chinook of western Canada is a foehn wind.
* Fog- A cloud touching the ground caused by the cooling of moist air to below its dew point by the process of heat radiation. Radiation fog usually forms near the surface at night under clear skies and light wind conditions. Also known as ground fog.
* Fog-A cloud that forms at or very close to ground level.
* Fold-A bend in rock.
* Foliation-Layering in rock created by metamorphism.
* Footwall-The rock beneath an inclined fault.
* Forearc basin-A sedimentary basin between the trench and the magmatic arc either in an island arc or Andean continental margin.
* Foreshock-Small earthquakes that precede a large quake by an interval ranging from a few seconds to a few weeks.
* Foreshore-The zone that lies between the high and low tides; the intertidal region.
* Formation-A lithologically distinct body of sedimentary, igneous, or metamorphic rock that can recognized in the field and can be mapped.
* Fossil- Evidence of past life on earth. Can include the preserved hard and soft parts of plants and animals, tracks and burrows, whole organisms preserved intact in amber or tar, and fossilized dung. ANY evidence of life constitutes a fossil.
* Fossil fuel-Fuels formed from the partially decayed remains of plants and animals. The most commonly used fossil fuels are petroleum, coal, and natural gas.
* Fossil fuels- nonrenewable fuels formed from the remains of plants and animals that lived long ago (oil, coal, natural gas, etc.)
* Fossil-The preserved trace, imprint, or remains of a plant or animal.
* Fracture - In minerals, a break along an uneven (non-planar) surface.
* Fracture-(1) The manner in which minerals break other than along planes of cleavage. (2) A crack, joint, or fault in bedrock.
* Freezing Rain- Rain that falls as liquid drops but freezes upon impact with horizontal or vertical surfaces. Freezing rain is characterized as either glaze or rime depending on the nature of the ice. Rain may freeze on the surface because its drops are supercooled and freeze on contact or that the surface is well below freezing. Technically, only the former is considered freezing rain, but the public usually considers any rain that falls and is observed frozen as freezing rain.
* Front- the boundary between two unlike air masses.
* Frontal weather system-A weather system that develops when air masses collide.
* Frontal wedging-A condition in which a moving mass of cool, dense air encounters a mass of warm, less dense air; the cool, denser air slides under the warm air mass, forcing the warm air upward to create a weather front.
* Front-In meteorology, a line separating air masses of different temperature or density.
* Frost- The deposition of ice crystals on a surface directly from the water vapor in the atmosphere. The process is similar to dew formation except that the temperature of the object must be below freezing, the frost point.
* Frost wedging-A process in which water freezes in a crack in rock and the expansion wedges the rock apart.
* Frost-Ice crystals formed directly from vapor.
* Fuel rod-A 2 meter-long column of fuel-grade uranium pellets used to fuel a nuclear reactor.
* Fujita Scale or Fujita Tornado Intensity Scale- The Fujita Scale (generally F0 to F5) for Tornado Intensity is used to rate the intensity of a tornado by examining the damage caused by the tornado after it has passed over a human-made structure. The scale was developed by the late Dr T. Theodore Fujita of the University of Chicago.
* Fusion (of atomic nuclei)-The combination of nuclei of light elements (particularly hydrogen) to form heavier nuclei.
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