Geology 141 Terms UO

Subpolar low

A belt of low pressure at the surface, produced by warm and moist air from a subtropical high rising over denser cold and dry polar air

Mountain breeze

A breeze that flows downward; results from a greater radiative heat loss from the mountain slopes at night and the resulting increase in density.

Younger Dryas

A brief return to full glacial conditions about 13,000 years ago that occurred early in the warming period following the last glacial maximum; thought to have been caused by changes in North Atlantic Ocean circulation.

Paleocene Eocene Thermal Maximum (PETM)

A brief spike in Earth's warmth that occurred about 55 million years ago.

Theory

A comprehensive body of explanatory knowledge that is both widely supported by experiment and generally accepted among scientists

General circulation model

A computer model that can be run indefinitely, with constant or varying forcing values (external factors). Widely used to assess the role humans have played in climatic change and to project the effects of continued release of greenhouse gases.

Jet stream

A concentrated, "river" of air. There are two high- altitude, west-to-east-flowing jets that are major features of the upper atmospheric circulation system poleward of latitude 15 degrees in both the Northern and Southern Hemispheres. Because of their general occurrence above the subtropical and subpolar latitudes, they are respectively known as the subtropical jet stream and the polar front jet stream. A third such corridor of high-altitude, concentrated wind flow is the tropical easterly jet stream, a major feature of the upper air circulation equatorward of latitude 15 degrees N. This third jet stream, however, flows in the opposite, east-to-west direction and occurs only above the tropics of the Northern Hemisphere.

Advection fog

A fog that occurs when fairly moist air moves over a colder surface and loses enough heat to reach the condensation point.

Experiment

A general term involving a procedure or test that is designed to learn more about a hypothesis

Global warming

A general term that refers to an observed temperature increase over the past 150 years.

Hot-house climate

A generally warm climate with little permanent ice like that in today's icecaps. Hot-house climates typically last hundreds of millions of years and have been the norm throughout Earth history.

Rhumb line

A line of constant compass bearing. Rhumb lines appear as straight lines on the Mercator map projection, but as curving arcs on most others

Global warming pause

A now-discredited theory that there has been a hiatus in global warming over the last fifteen years.

La Nina

A pattern in the tropical Pacific Ocean consisting of anomalously cold sea-surface temperatures, stronger than normal trade winds, and increased precipitation in the western Pacific. La Nina's are in contrast to El Nino events.

Divergence A

A pattern of wind such that density decreases in the downstream direction. It can occur because winds blow away from a common location (such as outward from the center of a surface high pressure system) or because the air speeds up along the direction of flow.

Convergence

A pattern of wind such that density increases in the downstream direction. It can occur because winds from different directions blow toward the same location (as in the center of a surface low pressure system) or because the air slows down along the direction of flow.

Scientific method

A process consisting of certain elements that together constitute a convention for obtaining facts or learning the "truth" about phenomena of interest

Positive feedback mechanism

A process that acts to amplify change in a system

Negative feedback mechanism

A process that acts to resist or counteract change in a system

Adiabatic process

A process that does not involve the addition or removal of heat. Over a short period of time a rising or sinking air parcel gains little heat from its surroundings, and it follows an adiabatic process to a close approximation

Climate classification system

A set of rules based on observed climatic variables that produces a relatively small number of distinct climatic types.

Equilibrium

A system is in equilibrium with respect to some property if that property is unchanging over time

Ellipsoid

A three-dimensional object that is elliptical in cross- section

Degree

A unit used to specify the size of an angle, which ranges from zero to 360 for a full circle. Latitude and longitude are almost always specified in degrees

Kelvin scale

Absolute temperature scale used by scientists, based on the temperature of absolute zero (-273°C [-459.4°F]). A kelvin is identical to a Celsius degree (°C), so that water boils at 373 K (100°C) and freezes at 273 K (0°C)

Saturated air

Air that is holding all the water vapor molecules it can possibly contain at a given temperature

Rossby waves

Also called longwaves, airstreams that curve north and south as they move air generally eastward. They develop as a dynamic response to the equator-to-pole temperature gradient and are also affected by Earth topography and land/ ocean contrasts

Ice-house climate

Also known as glacial climates, relatively brief periods of colder temperatures on Earth, generally lasting only tens of millions of years having large areas of permanent (year-round) ice.

Surface layer

Also known as the friction layer, the lower troposphere where frictional forces are important, generally the lowest 500 to 2000 m (1640 to 6562 ft) of the atmosphere. Above this layer frictional effects on wind flow are negligible

Evaporation

Also known as vaporization, the process by which water changes from the liquid to the gaseous (water vapor) state. It takes about 2260 kilojoules of energy to change 1 kg (2.2 lb) of water from liquid to water vapor.

Actual evapotranspiration (AE)

Amount of water that is lost to the atmosphere from the surface by the combination of evaporation and transpiration.

Vertical datum

An agreed-upon standard for specifying elevation. The datum corresponds to "sea level" or zero elevation. Several vertical datums are in use, just as there are multiple horizontal datums (standards for longitude and latitude)

Model

An idealized representation of reality demonstrating specific aspects of interest to the researcher

Water balance

Analogous to an accountant's record (which tallies income, expenditures, and the bottom-line balance), the measurement of the inflow (precipitation), outflow (evapotranspiration), and net annual surplus or deficit of water at a given location.

Latitude

Angular distance, measured in degrees north or south, of a point on Earth's surface

Latent heat

"Hidden" heat involved in the processes of melting, freezing, evaporation, and condensation (see latent heat of fusion; latent heat of vaporization)

GIS

(see Geographic information system)

Primary circulation

(see general circulation)

Precipitation

Any liquid water or ice that falls to the Earth's surface through the atmosphere (rain, snow, sleet, and hail).

System

Any set of related objects or events and their interactions

Time zone

Approximately 15-degree-wide longitudinal zone, extending from pole to pole, that shares the same local time. In the conterminous United States, from east to west, the time zones are known as Eastern, Central, Mountain, and Pacific. Figure 4.8 displays the global time zone pattern, which involves many liberties with the ideal 15-degree subdivision scheme

Natural landscapes

Areas of the planet still essentially subject to natural physical processes

Geographic information system (GIS)

Assemblage of computer hardware and software that permits spatial data to be collected, recorded, stored, retrieved, manipulated, analyzed, and displayed to the user

Early Anthropocene hypothesis

Asserts that humans began modifying global climate about 8,000 years ago.

Circle of illumination

At any given moment on our constantly rotating planet, the boundary between the halves of the Earth that are in sunlight and darkness

Northern Hemisphere

Atmospheric carbon dioxide concentrations tend to be highest over

Anticyclone

Atmospheric high-pressure cell. Low-level anticyclones are characterized by sinking motion and spiraling airflow out of the central area of high pressure. In the Northern Hemisphere, winds flow clockwise around an anticyclone; in the Southern Hemisphere, winds flow counterclockwise around an anticyclone

Upper atmosphere

Atmospheric level above the surface friction layer.

Photosynthesis

Atmospheric oxygen in the atmosphere comes primarily from

Cyclone

Atmosphericlow-pressurecellinvolvingtheconvergence of air at low levels, which flows into and spirally rises at the center. The isobars around a cyclone are generally circular in shape, with their values decreasing toward the center. In the Northern Hemisphere, winds flow counterclockwise around a cyclone; in the Southern Hemisphere, winds flow clockwise around a cyclone.

Atmosphere

Blanket of air that adheres to the Earth's surface and contains the mixture of gases essential to the survival of all terrestrial life-forms as well as liquid and solid particulates

Dry conveyor belt

Brings cold and dry air from the middle and upper troposphere into a cyclone.

Daylight-saving time

By law, all clocks in a time zone are set one hour forward from standard time for at least part of the year. In the United States, localities (e.g., the state of Arizona) can exempt themselves from such federal regulations

Cold-air drainage

Category of local-scale wind systems governed by the downward oozing of heavy, dense, cold air along slopes under the influence of gravity; produces katabatic winds (such as southeastern France's mistral) that are fed by massive pools of icy air that accumulate over such major upland regions as the Alps and the Rocky Mountains

Gyre

Cell-like circulation of surface currents that often encompasses an entire ocean basin. For example, the subtropical gyre of the North Atlantic Ocean consists of the huge loop formed by four individual, continuous legs the North Equatorial, Gulf Stream, North Atlantic Drift, and Canaries currents.

Melting

Change from the solid state to the liquid state. It takes about 336 kilojoules of energy to change 1 kg (2.2 lb) of water from a solid into a liquid.

Great circle

Circle formed along the edge of the cut when a sphere is cut in half. On the surface of the sphere, that circle is the shortest distance between any two points located on it

Anthropogenic climate change

Climate change arising from human activity as opposed to natural processes.

Microclimate

Climate on a localized scale.

Cumulus

Cloud category that encompasses thick, puffy, billowing masses that often develop to great heights; subclassified according to height.

Cirrus

Cloud category that encompasses thin, wispy, streak- like clouds consisting of ice particles rather than water droplets; occur only at altitudes higher than 6,000 m (20,000 ft).

Fog

Cloud layer in direct contact with the Earth's surface.

Eye wall (hurricane)

Cloud-filled rim of the eye at the center of a well-developed hurricane. The tropical cyclone's strongest winds and heaviest rainfall occur here.

Stratus

Cloud-type category encompassing layered and fairly thin clouds that cover an extensive geographic area; subclassified according to height

Cryosphere

Collective name for the ice system of the Earth, which constitutes one of the five subsystems of the total Earth system

Evapotranspiration

Combined processes by which water (1) evaporates from the land surface and (2) passes into the atmosphere through the leaf pores of plants (transpiration).

Isarithmic mapping

Commonly used cartographic device to represent three-dimensional volumetric data on a two- dimensional map; involves the use of isolines to show the surfaces that are mapped

Hydrologic cycle

Complex system of exchange involving water in its various forms as it continually circulates among the atmosphere, lithosphere, hydrosphere, cryosphere, and biosphere (see Fig. 11.3).

Subsystem

Component of a larger system. It can act independently, but operates within, and is linked to, the larger system

Parallelism

Constant tilt of the Earth's axis (at 66.5 degrees to the plane of the ecliptic) that remains parallel to itself at every position in its annual revolution of the Sun

Global positioning system (GPS)

Constellation of more than two-dozen linked orbiting satellites that broadcast signals to portable receivers anywhere on the Earth's surface. The simultaneous detection of these signals enables the precise calculation of the receiver's latitude, longitude, and elevation

Front (weather)

Contact surface between two dissimilar air masses This narrow boundary zone usually marks relatively abrupt transition in air density, temperature, and humidity. A moving front is the leading edge of the air mass built up behind it.

Electromagnetic spectrum

Continuum of electric and magnetic energy, as measured by wavelength, from the high- energy shortwave radiation of cosmic rays to the low-energy longwave radiation of radio and electric power

Holocene

Current interglacial epoch, extending from 11,700 years ago to the present on the geologic timescal

Winter solstice

Day each year of the poleward extreme in latitude in the opposite hemisphere where the Sun's noontime rays strike the Earth's surface vertically. In the Northern Hemisphere, that date is December 22, when the Sun is directly above latitude 23.5 degrees S (the Tropic of Capricorn); in the Southern Hemisphere, that date is June 22, when the Sun is directly above latitude 23.5 degrees N (the Tropic of Cancer)

Summer Solstice

Day with the most hours of sunlight and the fewest hours of darkness

International date line

Definition 11 (of 30 active) For the most part a line that is antipodal to the prime meridian and follows the 180th meridian. Crossing the line toward the west involves losing a day, whereas crossing the line toward the east means gaining a day

Monsoon

Derived from the Arabic word for "season," a seasonal reversal of windflow and pressure found in various places around the planet (most spectacularly in Southeast Asia). The moist onshore winds of summer bring the wet monsoon, whereas the offshore winds of winter are associated with the dry monsoon.

Sahel

Derived from the Arabic word for shore, the name given to the east west semiarid (BSh) belt that constitutes the southern shore of North Africa's Sahara; straddles latitude 15 degree N and stretches across the entire African continent (see Fig. 14.3). Suffered grievous famine in the 1970s that killed hundreds of thousands and since then has periodically been devastated by severe droughts.

Thermohaline circulation

Describes the deep-sea system of oceanic circulation, which is controlled by differences in the temperature and salinity of subsurface water masses.

Radiation fog

Develops at night during clear skies, when the surface and lower atmosphere are cooled efficiently by radiation.

Aspect

Directional orientation of a steep mountain slope. In the Northern Hemisphere, southerly aspects receive far more solar radiation than do northward-facing slopes, with all the environmental consequences such a differential implies

Frictional force

Drag that slows the movement of air molecules in contact with, or close to, the Earth's surface; varies with the "roughness" of the surface. There is less friction with movement across a smooth water surface than across the ragged skyline of a city center

Rain shadow effect

Dry conditions—often at a regional scale, as in the U.S. interior West—which occur on the leeward side of a mountain barrier that experiences orographic precipitation. The loss of moisture as air flows upward on the windward side together with adiabatic warming and falling relative humidity on descent greatly reduces the chances for precipitation in the rain shadow.

Summer solstice

Each year, day of the poleward extreme in the latitude where the Sun's noontime rays strike the Earth's surface vertically. In the Northern Hemisphere that latitude is 23.5 degrees N (the Tropic of Cancer) and the date is June 22; in the Southern Hemisphere that latitude is 23.5 degrees S (the Tropic of Capricorn) and the date is December 22

Azores High

Eastern segment of the North Atlantic Ocean's semipermanent subtropical high-pressure cell (often called the Bermuda High) that is usually centered above the Azores Islands; an important component of the North Atlantic Oscillation (NAO).

Solstice

Either of the two times of the year when the sun is at its greatest distance from the celestial equator

Potential energy

Energy an object has by virtue of its position relative to another object.

Sensible heat flow

Environmental heat we feel or sense on our skins

Doldrums

Equatorial zone of periodic calm seas and unpredictable breezes where the Northeast and Southeast Trades converge. The crews of sailing ships dreaded these waters because their vessels risked becoming stranded in this becalmed marine environment

Anthropocene

Era of geologic time referring to the period when humanity's impact on global ecosystems has become significant.

Cold conveyor belt

Exists in the lower troposphere ahead of a warm front in a midlatitude cyclone. It flows toward the center of the low, parallel to the warm front.

Windward

Exposed, upwind side of a topographic barrier that faces the winds that flow across it

Source region

Extensive geographic area, possessing relatively uniform characteristics of temperature and moisture, where large air masses can form.

Polar cell

Feature of the 3-cell model of atmospheric general circulation found at high latitudes in both hemispheres. Centered over the poles, they consist of high pressure at the surface and descending air. Air flowing out of the high gives rise to the polar easterlies.

Climatic controls

Features of the Earth's surface such as the distribution of land and water bodies, ocean currents, and highlands that shape the climate of a locale by influencing its temperature and moisture regimes.

Dew

Fine water droplets that condense on surfaces at and near the ground when saturated air is cooled.

Gravity

Force of attraction that acts among all physical objects as a result of their mass (quantity of material of which they are composed)

Coriolis force

Force that, owing to the rotation of the Earth, tends to deflect all objects moving over the surface of the Earth away from their original paths. In the absence of any other forces, the deflection is to the right in the Northern Hemisphere and to the left in the Southern Hemisphere; the higher the latitude, the stronger the deflection

Urban heat island

Form taken by an isotherm representation of the heat distribution within an urban region. The central city appears as a "highland" or "island" of higher temperatures on a surrounding "plain" of more uniform (lower) temperatures

Cyclogenesis

Formation, evolution, and movement of midlatitude cyclones.

Scientific laws

Fundamental principles believed to hold without exception, for example, Newton's law

Continental shelf

Gently sloping, relatively shallow submerged plain just off the coast of a continent, extending to a depth of ca. 180 m (600 ft/100 fathoms)

Climatology

Geographic study of climates. This includes not only climate classification and the analysis of climates' regional distribution, but broader environmental questions that concern climate change, interrelationships with soil and vegetation, and human-climate interaction

Biogeography

Geography of plants (phytogeography) and animals (zoogeography)

Physical geography

Geography of the physical world. Figure 1.2 diagrams the subfields of physical geography

General circulation

Global atmospheric circulation system of wind belts and semipermanent pressure cells. In each hemisphere, the former include the Trades, westerlies, and polar easterlies. The pressure belts include the equatorial low (ITCZ) and, in each hemisphere, the subtropical high, upper midlatitude low, and polar high.

Global conveyor belt

Global system caused by thermohaline circulation, which moves masses of water throughout the world ocean.

Cold currents

Global-scale ocean currents that flow toward the equator.

Warm currents

Global-scale ocean currents that travel from the tropics toward the poles, usually exhibiting temperatures that deviate by only a few degrees from those of the surrounding sea, although larger ranges in temperature can be found at the regional scale

Representative concentration pathways (RCPs)

Greenhouse gas concentration scenarios for the future; used in general circulation models to project climatic responses to anthropogenic greenhouse gas emissions.

Hemisphere

Half-sphere; used precisely, as in Northern Hemisphere (everything north of 0 degrees latitude), or sometimes moregenerally, asinlandhemisphere(thesignificantconcentration of landmasses on roughly one side of the Earth)

Thermal energy

Heat

Soil heat flow

Heat conducted into and out of the Earth's land surface; also known as ground heat flow

Latent heat of fusion

Heat energy involved in melting, the transformation of a solid into a liquid. A similar amount of heat is given off when a liquid freezes into a solid.

Latent heat of vaporization

Heat energy involved in the transformation of a liquid into a gas or vice versa.

Ground heat flow

Heat that is conducted into and out of the Earth's surface; also known as soil heat flow

Convection

Heat transfer accomplished by fluid flow, such as wind, ocean currents, or rising air. Within the atmosphere, the heat transfer can result from the relative warmth or moisture of the moving air or water vapor. These are known respectively as sensible and latent heat transfer

Latent heat transfer

Heat transfer associated with the flow of water vapor

Midoceanic ridge

High submarine mountain ranges, part of a global system of such ranges that mark the location of divergent plate boundaries, most often found in the central areas of the ocean basins. Here new crust is formed by upwelling magma, which continuously moves away toward the margins of the ocean basins

Polar easterlies

High-latitude wind belt in each hemisphere, lying between 60 and 90 degrees of latitude. The Coriolis force is strongest in these polar latitudes, and the equatorward-moving air that emanates from the polar high is sharply deflected in each hemisphere to form the polar easterlies.

Equatorial jet stream

High-level wind belt blowing from east to west found at low latitudes.

Advection

Horizontal movement of material in the atmosphere.

Santa Ana wind

Hot, dry, foehn-type wind that occasionally affects Southern California. Its unpleasantness is heightened by the downward funneling of this air flow from the high inland desert through narrow passes in the mountains that line the Pacific Coast

Axis (Earth's)

Imaginary line that extends from the North Pole to the South Pole through the center of the Earth. The planet's rotation occurs with respect to this axis

Fall (autumnal) equinox

In Northern Hemisphere terminology, equinox that occurs when the Sun's noontime rays strike the equator vertically around September 23

Spring(vernal) equinox

In Northern Hemisphere terminology, the equinox that occurs when the Sun's noontime rays strike the equator vertically on or around March 21

Summer

In Northern Hemisphere terminology, the season that begins on the day of the summer solstice (June 22) and ends on the day of the fall (autumnal) equinox (around September 23)

Winter

In Northern Hemisphere terminology, the season that begins on the day of the winter solstice (December 22) and ends on the day of the spring (vernal) equinox (around March 21)

Forcings

In a general-circulation model, an external factor, such as Earth's topography, solar radiation, or atmospheric composition.

Interactive mapping

In geographic information systems (GIS) methodology, the constant dialogue between the map user and the maping program

Insolation

Incoming solar radiation

Temperature

Index used to measure the thermal energy of matter. In gases most of this energy is in the form of kinetic energy possessed by the moving molecules; the more kinetic energy they have, the faster they move. In solids the energy is mainly vibrational, as atoms oscillate around their average position

Small circles

Individual parallels splitting Earth in unequal pieces, each smaller than Earth's circumference

Thermometer

Instrument for measuring temperature. Most commonly these measurements are made by observing the expansion and contraction of mercury inside a glass tube

Barometer

Instrument that measures atmospheric pressure; invented by Torricelli in 1643

Tropical storm

Intensified tropical depression, exhibiting a deep central low-pressure cell, rotating cyclonic organization, and wind speeds between 21 and 33 m/s (39 and 74 mi/h). Further intensification would transform the system into a hurricane.

Equatorial low

Intertropical convergence zone (ITCZ) or thermal low-pressure belt of rising air that straddles the equatorial latitudinal zone; fed by the wind flows of the converging Northeast and Southeast Trades.

Water vapor

Invisible gaseous form of water; a highly variable atmospheric gas found mainly in the troposphere.

Subtropical jet stream

Jet stream of the upper atmosphere that is most commonly located above the subtropical latitudes; evident throughout the year

Mistral winds

Katabatic wind flow, affecting France's Rhône Valley each winter, which involves the cold-air drainage of the massive pool of icy air that accumulates over the nearby high- lying French and Swiss Alps

Boiling point (water)

Key setting in the calibration of temperature scales. On the Celsius scale water boils at 100°C, whereas on the Fahrenheit scale water boils at 212°F

Continental effect

Lack of the moderating influence of an ocean on air temperature, which is characteristic of inland locations; this produces hotter summers and colder winters relative to coastal locations at similar latitudes

Cultural landscapes

Landscapes in which human intervention dominates to such an extent that physical processes have become subordinate

Dry adiabatic lapse rate (DALR)

Lapse rate of an air parcel not saturated with water vapor: -1°C/100 m (-5.5°F/1,000 ft)

Polar high

Large semipermanent high-pressure cell centered approximately over the pole in the uppermost latitudes of each hemisphere.

Abyssal plain

Large zone of relatively low-relief seafloor, constituting one of the deepest areas of an ocean basin

Ocean currents

Large-scale movements of water that form the oceanic counterpart to the atmospheric system of wind belts and semipermanent pressure cells.

Last glacial maximum

Last period on Earth in which the ice sheets were at their greatest extension, about 20,000 years ago.

Arctic Circle

Latitude (66.5°N) marking the southern boundary of the Northern Hemisphere portion of the Earth's surface that receives a 24-hour period of sunlight or darkness

Antarctic Circle

Latitude (66.5°S) marking the northern boundary of the Southern Hemisphere portion of the Earth's surface that receives a 24-hour period of sunlight or darkness

Standard parallel

Latitude of tangency between a globe and the surface onto which it is projected.

Polar front

Latitudinal zone, lying at approximately 60 degrees N and S, where the equatorward-flowing polar easterlies meet the poleward-flowing westerlies. The warmer westerlies are forced to rise above the colder easterlies, producing a semipermanent surface low-pressure belt known as the subpolar low.

LiDAR

Light Detection and Ranging. LiDAR has various uses, perhaps the most important of which is for highly accurate surveys of ground surface elevation

Isoline

Line connecting all places possessing the same value of a given phenomenon, such as "height" above the flat base of the surface being mapped

Isobar

Line connecting all points having identical atmospheric pressure

Isohyet

Line connecting all points receiving an identical amount of precipitation

Isotherm

Line drawn on a weather map that connects points having identical temperature

Geography

Literally means Earth description. As a modern academic discipline, it is concerned with the explanation of the physical and human characteristics of the Earth's surface. "Why are things located where they are?" is the central question that geographical scholarship seeks to answer

Geomorphology

Literally means Earth shape or form; geography of landscape and its evolution, a major subfield of physical geography

Siberian High

Local name for northern Asia's polar high, which is centered over the vast north-central/northeastern region of Russia known as Siberia

Canadian High

Local name for northern North America's polar high, centered over far northwestern Canada

Bermuda High

Local name for the North Atlantic Ocean's subtropical high-pressure cell, which is generally centered over latitude 30 degrees N; also known as the Azores High

Hawai'ian High

Local name for the North Pacific Ocean's subtropical high-pressure cell, which is generally centered over latitude 30 degrees N; also known as the Pacific High

Aleutian Low

Local name for the northernmost Pacific Ocean's Upper Midlatitude Low, which is centered approximately at 60 degrees N near the archipelago constituted by Alaska's Aleutian Islands.

Thunderstorm

Local storm dominated by thunder, lightning, heavy rain, and sometimes hail.

Icelandic Low

Local term for the northernmost North Atlantic Ocean's upper midlatitude low, centered approximately at 60 degrees N near Iceland.

Eddies

Localized loops of water circulation detached from the mainstream of a nearby ocean current, which move along with the general flow of that current.

Antipode

Location on the exact opposite point of the near- spherical Earth. The North Pole is the antipode of the South Pole

Counterradiation

Longwave radiation emitted by the Earth's atmosphere downward toward the surface

Surface winds

Low-level winds within the friction layer. Such winds blow across the isobars instead of parallel to them, thus producing a flow of surface air out of high-pressure areas and into low-pressure areas at an oblique angle to the isobars. Surface wind speed is determined by the pressure gradient and the roughness of the surface

Absolute zero

Lowest possible temperature at which all molecules cease their motion; occurs at -273°C (-459.4°F) or 0°K (Kelvin).

Conformal map projection

Map projection that preserves the true shape of the area being mapped

Azonalflow

Meridional (north-south) flowof upper atmospheric winds (poleward of 15 degrees of latitude), particularly the subtropical and Polar Front jet streams. Periodic departures from the zonal (west-to-east) flow of these air currents are important because they help to correct the heat imbalance between polar and equatorial regions

Celsius scale

Metric temperature scale most commonly used throughout the world (the United States is an exception). The boiling point of water is set at 100°C and its freezing point at 0°C

Ice-crystal process

Most common process whereby precipitation forms and falls to Earth; rainfall in the tropical latitudes, however, is produced by the coalescence process.

Mercator map projection

Most famous of the cylindrical projections, one on which any straight line is a line of true and constant compass bearing

Tropic of Cancer

Most northerly latitude (23.5°N) where the Sun's noontime rays strike the Earth's surface vertically (on June 22, the day of the Northern Hemisphere summer solstice)

Tropic of Capricorn

Most southerly latitude (23.5°S) where the Sun's noontime rays strike the Earth's surface vertically (on December 22, the day of the Northern Hemisphere winter solstice)

Wind

Movement of air relative to the Earth's surface. Winds are always named according to the direction from which they blow

Chinook

Name given to the foehn winds that affect the leeward areas of mountain zones in the western plateaus of North America

Topography

Natural and artificial features found at the surface of an area

Eye (hurricane)

Nearly cloud-free vertical tube that marks the center of a hurricane, often reaching an altitude of 16 km (10 mi).

Carbon dioxide weathering feedback

Negative feedback process in which warming conditions lead to lower CO2 in the atmosphere, thereby causing cooling.

Meridional flow

North-south (azonal) movement of air.

Tornado Alley

North-south corridor in the eastern Great Plains of the central United States, which experiences tornadoes with great frequency; extends from central Texas northward through Oklahoma and Kansas to eastern Nebraska.

Prime meridian

North-south line on the Earth grid, passing through the Royal Observatory at Greenwich, London, defined as having a longitude of 0 degrees

Spring (season)

Northern Hemisphere season that begins at the spring (vernal) equinox around March 21 and ends at the summer solstice on June 22. The Southern Hemisphere spring begins at the equinox that occurs around September 23 and ends at the solstice on December 22

Valley breeze

Occurs as mountain terrain heats up rapidly in the sun, causing lower pressure to develop over the mountain ridges, spawning a breeze that flows upslope during the day

Deep ocean

Occurs at depths greater than 1,000 m and includes about 97 percent of the total ocean water volume.

Leap year

Occurs every fourth year, when a full day (February 29) is added to the calendar to allow for the quarter-day beyond the 365 days it takes the Earth to complete one revolution of the Sun

Feedback

Occurs when a change in one part of a system causes a change in another part of the system

Deposition (of water vapor)

Occurs when water moves from the vapor state to the solid state.

Subtropical gyre

Ocean circulation around the subtropical high that is located above the center of the ocean basin (see Fig. 10.4); dominates the oceanic circulation of both hemispheres, flowing clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere.

Thermocline

Ocean layer that extends beneath the mixed layer to a depth of about 1,000 m (3,300 ft) and is marked by a relatively sharp decrease in temperature with increasing depth.

Subpolar gyre

Oceanic circulation loop found only in the Northern Hemisphere. Its southern limb is a warm current steered by prevailing westerly winds, but the complex, cold returning flows to the north are complicated by sea-ice blockages and the configuration of landmasses vis-a-vis outlets for the introduction of frigid Arctic waters

Land breeze

Offshore air flow affecting a coastal zone, resulting from a nighttime pressure gradient that steers local winds from the cooler (higher-pressure) land surface to the warmer (lower- pressure) sea surface

Carbon dioxide levels have decreased and oxygen levels have increased

On average over the last 500 million years in the atmosphere

Meridian

On the Earth grid, a north-south line of longitude. These range from 0 degrees (prime meridian) to 180 degrees E and W (180 degrees E and W, of course, are the same line—the international date line [written simply as 180°])

Parallel

On the Earth grid, an east-west line of latitude. These parallels range from 0 degrees (equator) to 90 degrees N and S (the North and South Poles, respectively, where the east-west line shrinks to a point)

Calorie

One calorie is the amount of heat energy required to raise the temperature of 1 g (0.04 oz) of water by 1°C (1.8°F); not the same unit as the calories used to measure the energy value of food (which are 1,000 times larger).

Revolution

One complete circling of the Sun by a planet. It takes the Earth precisely one year to complete such an orbit

Equal-area map projection

One in which all the areas mapped are represented in correct proportion to one another

Conic map projection

One in which the transfer of the Earth grid is from a globe onto a cone, which is then cut and laid flat.

Cylindrical map projection

One in which the transfer of the Earth grid is from a globe onto a cylinder, which is then cut and laid flat

Planar map projection

One in which the transfer of the Earth grid is from a globe onto a plane, involving a single point of tangency

Conveyor belt

One of several broad air streams associated with a midlatitude cyclone.

Equinox

One of the two days (around March 21 and September 23) in the year when the Sun's noontime rays strike the Earth vertically at the equator. In Northern Hemisphere terminology, the March 21 event is called the spring (vernal) equinox and the September 23 event is called the fall (autumnal) equinox

Sea breeze

Onshore airflow affecting a coastal zone, resulting from a daytime pressure gradient that steers local winds from the cooler (higher-pressure) sea surface onto the warmer (lower- pressure) land surface.

Geostationary orbit

Orbit in which a satellite above the Equator revolves at the planet's rotational speed. Therefore the satellite is "fixed" in a stationary position above the same point along the Equator

Storm

Organized, moving atmospheric disturbance.

Lithosphere

Outermost shell of the solid Earth, lying immediately below the land surface and ocean floor (lithos means rock); composed of the Earth's thin crust together with the rigid uppermost portion of the mantle that lies just below.

Centrifugal force

Outward force experienced by objects following a curved path

Stratosphere

Ozone absorption of ultraviolet light is most pronounced in the

Equator

Parallel of latitude running around the exact middle of the globe, defined as 0° latitude

Hadley cell

Part of atmospheric general circulation found in the tropics and subtropics of both hemispheres. In cross-section the Hadley cells are like loops with air flowing toward the Equator at low levels, rising along the Equator, flowing poleward in the upper troposphere, and descending in the subtropics to complete the loop.

Transpiration

Passage of water into the atmosphere through the leaf pores of plants.

Diurnal temperature cycle

Pattern of temperature change during the course of a day

Annual temperature cycle

Pattern of temperature change during the course of a year.

Millennium

Period of 1,000 years.

Little Ice Age

Period of decidedly cooler global temperatures that prevailed from about 1400 to 1850. During these four centuries, mountain glaciers in most parts of the world expanded considerably.

Southern Oscillation

Periodic, change in pressure gradient in the atmosphere overlying the equatorial Pacific; associated with the occurrence of the El Nino and La Nina phenomena. (see Fig. 10.9).

El Niño

Periodic, large-scale, abnormal warming of the sea surface in the low latitudes of the eastern Pacific Ocean that produces a (temporary) reversal of surface ocean currents and air flows throughout the equatorial Pacific. These regional events have global implications, disturbing normal weather patterns in many parts of the world

Plane of the ecliptic

Plane in which Earth travels during its annual revolution around the Sun

Aphelion

Point in the Earth's orbit that occurs every July 4, where the distance to the Sun is at its maximum (ca. 152.5 million km [94.8 million mi])

Perihelion

Point in the Earth's orbit, which occurs every January 3, where the distance to the Sun is minimized (about 147.5 million km [91.7 million mi])

Zenith

Point in the sky directly overhead, 90 degrees above the horizon

Smog

Poor-quality surface-level air lying beneath a temperature-inversion layer in the lower atmosphere. The word is derived from the contraction of "smoke" and "fog"

Legend (map)

Portion of a map where its point, line, area, and volume symbols are identified

Ice-albedo feedback

Positive feedback process in which a change in snow cover and sea ice alters the albedo, which in turn affects snow and sea ice by modulating temperature.

Cyclonic precipitation

Precipitation associated with the passage of the warm and cold fronts that are basic components of the cyclones that shape the weather patterns of the midlatitudes; often used as a synonym for frontal precipitation.

Snow

Precipitation consisting of large ice crystals called snowflakes; formed by the ice-crystal process when crystals do not have time to melt before they reach the ground

Hail

Precipitation consisting of large ice pellets that do not melt before reaching the surface.

Rain

Precipitation consisting of large liquid water droplets.

Sleet

Precipitation consisting of pellets of ice produced by the freezing of rain before it reaches the surface; if it freezes after hitting the surface, it is called freezing rain.

Convergent-lifting precipitation

Precipitation produced by the forced lifting of warm, moist air where low-level wind flows converge; most pronounced in the equatorial latitudes, where the Northeast and Southeast Trades come together in the Intertropical Convergence Zone (ITCZ), especially over the oceans.

Convectional precipitation

Precipitation that occurs after condensation of air that rises because of instability.

Frontal precipitation

Precipitation that results from the movement of fronts whereby warm air is lifted, cooled, and condensed; also frequently called cyclonic precipitation.

Geodesy

Precise study and measurement of the size and shape of the Earth

Vapor pressure

Pressure exerted by the molecules of water vapor in air

Condensation

Process by which a substance is transformed from the gaseous to the liquid state

Freezing

Process by which a substance is transformed from the liquid to the solid state.

Sublimation

Process whereby a solid can change directly into a gas. The reverse process is sometimes also called sublimation, but is more properly called vapor deposition. The heat required to produce these transformations is the sum of the latent heats of fusion and vaporization.

Cold front

Produced when an advancing cold air mass hugs the surface and displaces other air as it wedges itself beneath the preexisting warmer air mass. Cold fronts have much steeper slopes than warm fronts and thus produce more abrupt cooling and condensation (and more intense precipitation).

Warm front

Produced when an advancing warm-air mass infringes on a preexisting cooler one. When they meet, the lighter warmer air overrides the cooler air mass, forming the gently upward-sloping warm front (usually producing more moderate precipitation than more steeply sloped cold fronts).

Oceanic trench

Prominent seafloor feature, often adjacent to an island arc, in a zone where two oceanic plates converge and one is subducted beneath the other. The greatest depths of the world ocean lie in such trenches in the Pacific east of the Philippines

Diffuse radiation

Proportion of incoming solar energy (22 percent) that reaches the Earth's surface after first being scattered in the atmosphere by clouds, dust particles, and other airborne materials

Direct radiation

Proportion of incoming solar energy that travels directly to the Earth's surface

Albedo

Proportion of incoming solar radiation that is reflected by a surface. Generally speaking the whiter the color of the surface the higher is its albedo (albedo derives from the Latin word albus, meaning white)

Relative humidity

Proportion of water vapor present in a parcel of air relative to the maximum amount of water vapor that air could hold at the same temperature.

Leeward

Protected side of a topographic barrier with respect to the winds that flow across it; often refers to the area downwind from the barrier as well, which is said to be in the "shadow" of that highland zone

Infrared radiation

Radiation at wavelengths longer than visible wavelengths, including longwave radiation (see terrestrial radiation and longwave radiation)

Shortwave radiation

Radiation coming from the Sun, which has much shorter wavelengths—and involves much higher energy—than the terrestrial (longwave, lower-energy) radiation emitted by the Earth

Terrestrial radiation

Radiation emitted by the Earth or objects at terrestrial temperatures (see longwave radiation)

Freezing rain

Rain that reaches the surface as liquid but then freezes after reaching the ground to form a layer of ice where it lands. Occurs when the layer of below-freezing air is not deep enough to freeze the falling rain.

Coalescence process

Raindrop-producing process that dominates in the tropical latitudes.

Orographic precipitation

Rainfall (and sometimes snowfall) produced by moist air parcels that are forced to rise over a mountain range or other highland zone.

Soil moisture

Rainwater or snowmelt that has infiltrated into the soil; is present in the ground in either the liquid or frozen state.

Temperature gradient

Rate of temperature change per unit distance, most often taken in the horizontal direction

Specific humidity

Ratio of the mass of water vapor in the air to the combined mass of the water vapor plus the air itself.

Scale

Ratio of the size of an object on a map to the actual size of the object it represents

Concave

Refers to a surface that is rounded inward, like the inside surface of a sphere

Convex

Refers to a surface that is rounded outward, like the outside surface of a sphere

Milankovitch cycles

Refers to cyclical changes in the shape of Earth's orbit, the degree of tilt of Earth's axis and the direction of tilt over periods of 100,000 years, 40,000 years, and 20,000 years. The cycles lead to variations in the seasonal and spatial distribution of sunlight reaching the planet and thereby have the potential to influence climate.

Disappearing climate

Refers to locations whose present-day climate is so dissimilar from climates found anywhere in the late twenty-first century that their climate is said to "disappear."

Extreme events

Refers to temperatures above or below some threshold, such as 90°F for extreme heat or -20°F for cold snaps.

Glacial/interglacial cycles

Refers to the glacial and interglacial periods throughout time, caused by variation in Earth�s orbit. Periods with large ice sheets are known as glacial periods, and periods with reduced ice cover (such as the present) are known as interglacial periods.

Teleconnections

Relationships involving long-distance linkages between weather patterns that occur in widely separated parts of the world; El Niño is a classic example.

Multispectral systems

Remote-sensing platforms capable of capturing radiation intensity in multiple spectral bands

Runoff

Removal of water that falls as precipitation, via the network of streams and rivers. Can refer to all of the water that is not evaporated or transpired, or just to the water that does not infiltrate into the soil but instead flows away over the land surface; in the latter case the term overland flow is also used.

Contouring

Representation of surface relief using isolines of elevation above sea level; an important basis of topographic mapping

Upwelling

Rising of cold water from the ocean depths to the surface; affects the local climatic environment because cold water lowers air temperatures and the rate of evaporation.

Cartography

Science, art, and technology of mapmaking and map use

Closed system

Self-contained system exhibiting no exchange of energy or matter across its boundaries (interfaces)

Subtropical high

Semipermanent belt of high pressure that is found at approximately 30 degrees of latitude in both the Northern and Southern Hemispheres. The subsiding air at its center flows outward toward both the lower and higher latitudes

Earth system

Shells or layers that make up the total Earth system range from those of the planet's deepest interior to those bordering outer space. This book focuses on the five key Earth layers: atmosphere, lithosphere, hydrosphere, cryosphere, and biosphere

Orders of magnitude

Sizes of geographic entities. Figure 1.8 shows the entire range of magnitudes, including those in which geographers usually operate

Freezing nuclei

Small airborne particles (such as dust and salt) around which ice crystals can form when liquid water freezes. Freezing nuclei enhance freezing and allow it to occur at relatively warm temperatures just a few degrees below 0oC (32oF).

Condensation nuclei

Small airborne particles around which liquid droplets can form when water vapor condenses; almost always present in the atmosphere in the form of dust or salt particles.

Tornado

Small vortex of air, averaging 100 to 500 m (330 to 1,650 ft) in diameter, that descends to the ground from rotating clouds at the base of a severe thunderstorm, accompanied by winds whose speeds range from 50 to 130 m/s (110 to 300 mi/h). As tornadoes move across the land surface, they evince nature's most violent weather and can produce truly awesome destruction in the natural and cultural landscapes.

Hydrosphere

Sphere of the Earth system that contains all the water that exists on and within the solid surface of our planet and in the atmosphere above

Rotation

Spinning of a planet on its axis, the imaginary line passing through its center and both poles. It takes the Earth one calendar day to complete one full rotation

Dynamic equilibrium

State of a system in balance despite the continual flow of energy and/or mass through the system. A landscape that is in dynamic equilibrium has a stable form over time, although it continues to erode

Continental slope

Steeply plunging slope that begins at the outer edge of the continental shelf (ca. 180 m [600 ft] below the sea surface) and ends in the depths of the ocean floor at the head of the continental rise

Ice age

Stretch of geologic time with large areas of permanent, year-round ice. Within an ice age ice cover expands and contracts in glacial/interglacial cycles. Earth is currently in an ice-age climate. The last glacial maximum was about 20,000 years ago; the present climate is an interglacial within the most recent ice age.

Dendrochronology

Study of the width of annual growth rings in trees.

Water resources

Subfield of physical geography involving its intersection with hydrology; systematic study of the surface and subsurface water supplies potentially available for human use

Mid-Atlantic Ridge

Submarine mountain range that forms the midoceanic ridge extending through the entire North and South Atlantic oceans, from Iceland in the north to near- Antarctic latitudes in the south; marks a divergent boundary between lithospheric plates

Submarine canyon

Submerged river valley on the continental shelf. Before the rise in sea level (of about 120 m [400 ft]) over the past 10,000 years, the shelf was mostly dry land across which the river flowed to its former outlet

Northeast Trades

Surface wind belt that generally lies between the equator and 30 degrees N; the Coriolis force deflects equatorward-flowing winds to the right, thus recurving north winds into northeast winds

Southeast Trades

Surface wind belt that generally lies between the equator and 30 degrees S. The Coriolis force deflects equatorward-flowing winds to the left, thus recurving south winds into southeast winds

Interface

Surface-like boundary of a system or one of its component subsystems. The transfer or exchange of matter and energy takes place here

Steady-state system

System in which inputs and outputs are constant and equal

Open system

System whose boundaries (interfaces) freely permit the transfer of energy and matter across them

El Nino Southern Oscillation (ENSO)

Systematic changes in temperature, precipitation and the flow of ocean currents and prevailing winds in the equatorial Pacific Ocean.

Hydrology

Systematic study of the Earth's water in all its states

Soil geography

Systematic study of the spatial patterns of soils, their distribution, and the interrelationships with climate, vegetation, and humankind

Meteorology

Systematic, interdisciplinary study of the short- term atmospheric phenomena that constitute weather.

Remote sensing

Technique for imaging objects without the sensor being in immediate contact with the local scene

Dew-point

Temperature at which air becomes saturated and below which condensation occurs.

Hypotheses

Tentative explanations of observations and measurements

Drift (ocean surface)

Term often used as a synonym for ocean current when the rate of movement lags well behind the average speeds of surface winds blowing in the same direction. Currents are characterized by a slow and steady movement that very rarely exceeds 8 km/h (5 mph)

Snowball Earth

Term used for the most extreme ice-house climates, called such because nearly the entire planet is covered with ice during these times.

Climatic normal

The 30-year average of a location's temperature, precipitation, wind speed, or any other climatic element. Climatic normals are updated every 10 years; currently the averaging period is 1981-2010

Potential evapotranspiration (PE)

The amount of water that would be lost to the atmosphere from an underlying well-watered vegetated surface. PE represents the atmosphere's demand for water. In dry climates PE is far in excess of actual evapotranspiration.

Angle of incidence

The angle at which incoming light rays approaches a surface.

Solar altitude

The angle of the Sun above the horizon

Net radiation

The difference between total absorbed radiation and emitted radiation, including both longwave and shortwave radiation. See Table 5.1 for global average values

Pressure-gradient force

The difference in surface pressure divided by the distance between two locations is called the pressure gradient. Pressure gradient gives rise to a force that causes air to move (as wind) from the place of higher pressure to that of lower pressure

Nitrogen

The most abundant gas in the atmosphere by both number of molecules and relative mass

Water vapor feedback

The net effect of increasing water vapor in global warming. Consists of the stronger positive feedback due to increased specific humidity and the weaker negative feedback caused by decreasing saturated adiabatic lapse rate.

Human-made chemicals released into the atmosphere

The ozone hole is caused primarily by

Gravitational potential energy

The potential energy an object possesses by virtue of its position above some reference level. When an object falls or moves downward potential energy is converted to kinetic energy, the energy of motion.

Gravitational force

The primary force exerting an influence on air molecules. The atmosphere is "held" against Earth by this force, and our planet would have no atmosphere at all were it not for gravity

Environmental lapse rate (ELR)

The rate at which temperature declines with altitude in a column of air. The troposphere's average (or "normal") lapse rate is -0.64°C/100 m (-3.5°F/1,000 ft)

Land hemisphere

The roughly one-half of the Earth that contains most of the landmasses (see Fig. 2.6); the opposite of the water (oceanic) hemisphere

Water (oceanic) hemisphere

The roughly one-half of the Earth that contains most of the surface water; the opposite of the land hemisphere

Mixed layer

The surface layer of an ocean, extending to about 75 m (245 ft) in depth and containing about 3 percent of the total ocean water volume.

Fahrenheit scale

The temperature scale on which water freezes at 32 degrees and boils at 212 degrees

Stability (of air)

The tendancy of an air parcel to rise or sink owing to buoyancy. The air is stable if air parcels return to their original positions after some upward movement. By contrast, if air parcels rise spontaneously (or after some initial force), the atmosphere is unstable

Intertropical Convergence Zone (ITCZ)

Thermal low-pressure belt of rising air whose average position is along the Equator; fed by the wind flows of the converging Northeast and Southeast Trades

Argon

This gas has both a relatively high molecular weight and no biological or chemical interactions and therefore has a nearly infinite residence time in the atmosphere

Waterspout

Tornado that forms and moves over a water surface.

Continental rise

Transitional zone of gently sloping seafloor that begins at the foot of the continental slope and leads downward to the lowest (abyssal) zone of an ocean basin

Radiation

Transmission of heat energy in the form of electromagnetic waves. The energy of each wave is inversely proportional to its wavelength (i.e., shorter waves are more energetic). The totality of wavelengths comprises the electromagnetic spectrum (see Fig. 3.19)

Conduction

Transport of heat energy from one molecule to the next

Hurricane

Tropical cyclone capable of inflicting great damage. A tightly organized, moving low-pressure system, originating at sea in the warm, moist air of the tropical atmosphere, exhibiting wind speeds in excess of 33 m/s (74 mi/h). Like other tropical cyclones, it has a distinctly circular wind and pressure field.

Tropical depression

Tropical cyclone exhibiting wind speeds of less than 21 m/s (39 mi/h). Further intensification of the depression would next transform it into a tropical storm.

Core (drilling)

Tube-like sample of seafloor sediment that is captured and brought to the surface in a hollow drill pipe. The drill pipe is thrust perpendicularly into the ocean floor, and the sample it brings up shows the sequence of sedimentary accumulation.

Westerlies

Two broad midlatitude belts of prevailing westerly winds, lying between approximately 30 degrees and 60 degrees in both hemispheres; fed by the Coriolis force-deflected poleward wind flow emanating from the subtropical high on the equatorward margin of the Westerlies wind belt

Seamount

Undersea abyssal-zone volcanic mountain reaching over 1,000 m (3,300 ft) above the ocean floor

Horizontal datum

Unique geographic coordinate system created by examining a model ellipsoid and its related parameters

Polar front jet stream

Upper-atmosphere jet stream located above the subpolar latitudes, specifically the polar front; at its strongest during the winter season.

Continentality

Variation of the continental effect on air temperatures in the interior portions of the world's landmasses; the farther the distance from the moderating influence of an ocean (known as the maritime effect), the greater the extreme in summer and winter temperatures (northeastern Eurasia is the classic example of such extreme annual temperature cycles)

North Atlantic Oscillation

Variations in the pressure gradient between the North Atlantic Ocean's semipermanent upper midlatitude low-pressure cell (the Icelandic Low) and its semipermanent subtropical Azores high-pressure cell. Its fluctuations affect the warmth and moisture of wind flows in Europe, and the NAO's complicated workings also involve the North Atlantic Drift ocean current, the sinking of warm water near Greenland and Iceland, the upwelling of cold water off northwest Africa, and many lesser components.

Subsidence

Vertical downflow of air toward the surface from higher in the troposphere

Air mass

Very large parcel of air (more than 1,600 km [1,000 mi] across) in the troposphere whose density, temperature, and humidity is relatively uniform in the horizontal dimension. Air masses can retain their properties for a week or more and routinely migrate for hundreds of kilometers as distinct entities.

Cumulonimbus

Very tall cumulus clouds, extending from about 500 m (1,600 ft) at the base to over 10 km (6 mi) at the top, often associated with violent weather involving thunder, lightning, and heavy winds and rains.

Cloud

Visible mass of suspended, minute water droplets and/ or ice crystals.

Easterly wave

Wavelike perturbation in the prevailing easterly flow of the Northeast and Southeast Trades, which produces this type of distinctive weather system. Westward-moving air is forced to rise on the upwind side (producing often-heavy rainfall) and descend on the fair-weather downwind side of the low- pressure wave trough.

Pressure (atmospheric)

Weight of a column of air per unit area at a given location, determined by the acceleration of gravity and the mass of atmosphere at that location. Standard sea-level air pressure produces a reading of 760 mm (29.92 in) on the mercury barometer. In terms of pressure, it is also given as 1,013.25 millibars (mb), or 14.7 lb/in2

Adiabatic lapse rate

When a given mass of air expands, its temperature decreases. If a parcel of air rises to a higher altitude, it expands and cools adiabatically. Its lapse rate is therefore referred to as an adiabatic lapse rate

Greenhouse effect

Widely used but imperfect analogy describing the blanket-like effect of the atmosphere in the heating of the Earth's surface. Shortwave insolation passes through the "glass" of the atmospheric "greenhouse"; heats the surface; is converted to longwave radiation, which cannot penetrate the "glass"; and thereby results in the trapping of heat that raises the temperature inside the "greenhouse"

Zonal flow

Wind blowing primarily along a parallel of latitude (east-west).

Geostrophic wind

Wind that results when the Coriolis and pressure-gradient forces balance each other out. Geostrophic wind has a constant speed and direction and blows parallel to straight isobars (see Fig. 8.7)

Storm surge

Wind-driven wall of water hurled ashore by the approaching center of a hurricane, which can surpass normal high-tide levels by more than 5 m (16 ft); often associated with a hurricane's greatest destruction.

Katabatic winds

Winds that result from cold-air drainage; especially prominent under clear conditions where the edges of highlands plunge sharply toward lower-lying terrain

Biosphere

Zone of terrestrial life, the habitat of all living things; includes the Earth's vegetation, animals, human beings, and the part of the soil layer below that hosts living organisms

Dust dome

a dome of heated air that surrounds an urban area and contains a lot of air pollution

Kinetic energy

energy of motion

saturated adiabatic lapse rate (SALR)

is the rate at which the temperature of a parcel of air saturated with water vapour (or a parcel of air undergoing the process of condensation) changes as the parcel ascends or descends. - The ______ is not constant since it varies strongly with temperature. Since there is more water vapour in warm air than in cold air, the condensation rate, and thus the heating rate, decreases as the temperature of the air parcel decreases. - The _______ varies from+3°C/km(high temperature near surface) to +9.78 °C/km (very low temperature). However, at temperatures above freezing it is usually near +4.9 °C/km.

Maritime effect

moderating influence of the ocean on air temperature, which produces cooler summers and warmer winters relative to inland locations at similar latitudes

Mathematical projections

sMaps that do not use a projection surface such as a cylinder or cone.

Winter Solstice

shortest day of the year

Prevailing Westerlies

winds that blow west to east between 30 and 60 degrees in the northern and southern hemispheres