Copy of `Southeast Regional Climate Center - Climate terms`

The wordlist doesn't exist anymore, or, the website doesn't exist anymore. On this page you can find a copy of the original information. The information may have been taken offline because it is outdated.

Southeast Regional Climate Center - Climate terms Category: Meteorology and astronomy > Weather and Climate Date & country: 21/10/2013, USA Words: 165

acid rain
rain having a pH lower than 5.6 (the pH of natural rainwater), usually caused by sulfuric acid and/or nitric acid from air pollution.

advection
Horizontal transport of temperature, pressure, moisture or some other atmospheric attribute solely by the wind.

aerosol
particulate matter put into the atmosphere. Examples are smoke and dust.

air mass
a body of air that has the same temperature, moisture, and stability properties.

altimeter
an instrument that measures the altitude of something with respect to a set level.

altitude
the vertical distance above a certain level, usually sea level or ground level.

altocumulus
a middle cloud type that is white and/or gray in color and occurs as a layer or patch with a waved aspect. Generally have shadowed parts.

altostratus
a middle cloud type that appears as a gray or bluish sheet of stretched out, fibrous, or uniform appearance. Overcast clouds.

anemometer
an instrument that measures wind speed.

anticyclone
a body of air that circulates clockwise and outward in the Northern Hemisphere and counterclockwise and outward in the Southern Hemisphere, and is associated with a high atmospheric pressure.

anvil
the top part of a cumulonimbus cloud that is flat and spread out, with a shape that looks like a blacksmith's anvil.

aphelion
the point where the earth is farthest (152 million kilometers) from the sun while in its orbit. Currently, this occurs on July 5.

atmosphere
air enveloping earth due to earth's gravitational pull. Can be divided into layers radiating out from the surface in the following order- troposphere, stratosphere, mesosphere, thermosphere.

aurora
appears as greenish-white and sometimes pink light in the night sky over the middle and high latitudes. Called the aurora borealis in the Northern Hemisphere and the aurora australis in the Southern Hemisphere. Caused by electrons interacting with each other in the upper atmosphere.

barometer
instrument that measures atmospheric pressure.

Bermuda High
a subtropical anticyclone that occurs over the North Atlantic Ocean.

biosphere
the zone between the earth and the atmosphere in which most life forms reside.

black frost
when vegetation is frozen on the inside during a frost in which there is no moisture. A black frost will almost always kill the plant.

boiling point
The temperature at which a substance will change from a liquid state to a gas state. The boiling point of water is 100

calm
when the air conditions have no movement or wind.

calorie
the amount of heat required to raise the temperature of one gram of water one degree Celsius.

ceilometer
an instrument used to measure cloud height.

Celsius
term used to describe temperature based on the boiling point (100

cirriform
describes high clouds formed with small, mostly ice particles that result in white, transparent clouds that often produce a halo when the sun shines through them.

cirrus
a high cloud made up of ice crystals that appear fibrous and silky.

climatology
scientific study of the climate, the causes of a climate, and the use of data to solve climate related problems.

cold front
when a colder, higher pressure air mass moves so that cold air replaces warmer air. Storm activity is often associated with the moving in of a cold front.

condensation
when a vapor becomes a liquid due to some change. Occurs often when the temperature becomes cooler, the humidity becomes greater, or the air pressure changes.

conduction
transfer of energy through a body by particles or molecules within that body. Energy flows from the hotter parts to the cooler parts.

contrail
a trail of condensed water vapor formed by jet aircraft flying at high altitudes. This trail is formed by the water vapor added to the air by engine exhaust, as well as particles in the exhaust that act as cloud nuclei.

convection
vertical energy transfer in the atmosphere.

cooling degree day
a measurement used to determine how much fuel will be needed to cool indoor environments. There is one cooling degree-day unit for each degree that the mean daily temperature departs from 65

cumulonimbus
a dense cloud with a lot of vertical development that looks like a large tower. Often the top is flattened, and spreads out above the cloud in an anvil shape. This is a storm cloud, and is often associated with precipitation and severe weather.

cumulus
a low cloud that develops from the bottom up. Appear white and puffy, with a cauliflower-like top. Small ones are associated with fair weather(cumulus humilis), but as they grow vertically, they can produce rain showers (cumulus congestus).

current
a horizontal movement of water or air.

cyclone
a body of air that circulates counter clockwise and inward in the Northern Hemisphere and clockwise and inward in the Southern Hemisphere, and is associated with a low atmospheric pressure .

degree
1) a unit of temperature, describing an interval on a scale of Fahrenheit or Celsius. 2) a unit of angular distance, used to describe distance of latitude and longitude.

degree-day unit
a measure of how much the mean daily temperature differs from a base temperature in Fahrenheit and Celsius. Used to determine how much fuel will be needed to heat or cool indoor environments.

desertification
when an area begins to develop desert-like conditions due to lack of water, deforestation, overgrazing and over cropping.

dew
when liquid water from the atmosphere condenses on plants and objects near the ground.

dewpoint
the temperature that air must reach before condensation can occur. The air is saturated at this point.

diffuse sky radiation
the energy from the sun that is scattered by molecules, clouds and aerosols in the atmosphere.

direct radiation
the energy from the sun that hits the earth without being obstructed by clouds, molecules, or aerosols. It is the sunlight that creates a shadow at the surface.

diurnal
referring to daily phenomena.

drought
a long period of time where there is abnormally dry weather due to little or no precipitation.

dry adiabatic lapse rate
the rate at which an unsaturated parcel of air will decrease in temperature as it moves through the atmosphere. The rate is a decrease of about 9.767

dry season
in certain climates, it is a period of one month or more where precipitation is at a minimum.

dryline
a boundary that separates warm, dry air from warm, moist air. This boundary usually represents a zone of instability where thunderstorms often develop due to the mixing of the different types of air.

dust devil
a small rotating column of wind that can be seen due to the dust and debris that it picks up.

duststorm
when strong winds blow over a dusty area, blowing the dust into the air and reducing visibility significantly.

easterlies
winds that come from the East. Examples are equatorial easterlies, tropical easterlies (trade winds), and polar easterlies.

eclipse
when one celestial body, such as the sun or the moon, hides another from view.

El Ni
warming of ocean waters in the eastern tropical pacific, resulting in warmer waters off the coasts of Ecuador and northern Peru. Associated with heavy rainfall in those regions, and also affects weather patterns in North America as well. Usually begins to occur around Christmas, and is so named for El Ni

electromagnetic radiation
form of energy emitted through space and reaches the earth. Solar electromagnetic radiation comes from the sun and drives all energy processes on earth.

electromagnetic radiation spectrum
all the types of radiation put in order from smallest wavelength to largest wavelength. Please see table* below.

elevation
vertical distance from sea level to a point affixed to the ground. The elevation of a mountain, for example, may be 10,000 feet.

ENSO Cycle
El Ni

environmental lapse rate
the rate of decrease of air temperature as altitude increases. Is compared to the dry adiabatic lapse rate or moist adiabatic lapse rate to determine vertical motions of an air parcel.

equator
imaginary circle having 0

equinox
either of two points where the sun's rays will shine directly over the equator at noon, and all locations on earth will theoretically experience twelve hours of daylight. The vernal equinox occurs on March 21 and the autumnal equinox occurs on September 22 in the Northern Hemisphere. The dates are reversed for the Southern Hemisphere.

erosion
when rock and soil are moved from one place to another by running water, precipitation, ice, or wind.

evaporation
the change of state from a liquid to a vapor.

evapotranspiration
the combined water vapor put into the air through evaporation from water on earth's surface and plants giving off water to the atmosphere.

exosphere
the outermost portion of the atmosphere.

Fahrenheit
temperature scale where water freezes at 32

flash flood
a flood that rises and falls rapidly with little or no advance warning, usually due to intense rainfall over a small area.

flood
when water overflows the confines of a body of water and gathers over low-lying areas.

fog
a visible gathering of water droplets suspended in the air near the earth's surface.

freezing point
the temperature at which a substance changes from a liquid to a solid. For water, it is 0

From
MicroWorlds.

front
boundary where two air masses with different temperatures and moisture content meet.

frost
1) a cover of ice crystals produced when atmospheric water vapor is deposited directly on a surface when the temperature is below freezing, 2) the condition that exists when the temperature of the earth's surface and earth-bound objects falls below freezing. An example is a killing frost, where a frost will end the growing season in agriculture because it freezes crops and they die.

frost point
temperature where air is cooled enough to become saturated, but forms ice instead of dew.

Fujita Tornado Scale
classifies tornadoes from F0 (wind speeds of 40-72 mph) to F5 (261-318 mph) on the basis of rotational speeds derived from the damage they cause. Developed by T. Theodore Fujita.

funnel cloud
a quickly rotating column of air coming down from a cloud base but not reaching the ground. When it touches the ground it becomes a tornado.

greenhouse effect
a natural occurrence caused by certain greenhouse gases in the Earth's atmosphere. Because greenhouse gases trap longwave energy and reemit it back to the Earth's surface, the global temperature is changed 33 degrees Celsius, or 59 degrees Fahrenheit warmer than it would otherwise be. Some scientists think that the increase in greenhouse gases in the atmosphere (caused by pollution- mainly the burning of fossil fuels and deforestation) may be causing a rise in global temperature.

greenhouse gas
gases in the atmosphere that are more transparent to the short wavelength radiation (mostly visible light) from the sun, than to the long wavelength radiation (infrared radiation) leaving the Earth. These gases then reemit the trapped energy, partly toward the Earth's surface. Examples are carbon dioxide, methane, CFCs, and nitrous oxides.

Gulf Stream
a warm ocean current that flows from the Gulf of Mexico and the Carribean Sea north along the North American coast, and northeast across the Atlantic Ocean.

hail
frozen precipitation that looks like balls or lumps of ice. Usually produced by cumulonimbus clouds.

halo
a ring of light that appears to encircle the sun or moon. This occurs when the light from the sun or moon shines through cirrus clouds.

Heat Index
temperature that describes how hot it feels taking into account high air temperatures and high humidity levels.

heating degree day
a measurement used to determine how much fuel will be needed to heat indoor environments. There is one heating degree-day unit for each degree that the mean daily temperature departs from 65

high clouds
clouds found between 3-8 kilometers (10000-25000 feet) in polar regions and 6-18 kilometers (20000-60000 feet) in tropical regions. Contains cirriform clouds (cirrus, cirrocumulus, and cirrostratus).

high pressure system
area of maximum air pressure and anticyclonic air movement.

humidity
the measure of how much water there is in the air.

hurricane
a severe tropical cyclone with maximum 1-minute sustained surface wind speeds greater than 74 mph.

hydrologic cycle
the exchange of water between the earth, the oceans, and the atmosphere. Also called the water cycle.

hydrosphere
the part of planet earth that is covered with water and ice.

Indian summer
occurring during mid to late autumn after the first frost, a period of unusually warm weather with clear skies and cool nights.

infrared radiation
the portion of energy that has a wavelength between 0.8 micrometers (just above visible radiation) to 0.1 millimeters (microwave radiation).

instability
a state of the atmosphere when a parcel of air will keep moving either up or down from its starting position when moved. An unstable atmosphere is often associated with severe weather.

isobar
a line of equal pressure resembling a contour line on a map.

isotherm
a line passing through points of equal temperature on a map.

Kelvin
the SI (Standard International) unit of temperature. A degree symbol is not used. One Kelvin equals one degree Celsius, but the base temperature of Kelvin is absolute zero (-273

Knot
a measure of speed equal to the velocity of one nautical mile traveled in one hour. Usually used in marine studies. One knot equals 1.151 miles per hour or 1.852 kilometers per hour.

La Ni
a period of strong trade winds and abnormally low sea surface temperatures in the central and eastern tropical Pacific. It is the opposite of an El Ni

latent heat
heat released or absorbed per unit of mass when a substance changes phase. When water evaporates from liquid to steam, it absorbs heat. When liquid water freezes, it releases latent heat.

latitude
the distance in degrees on the earth measured from the equator, running horizontally. Lines of latitude are described as North or South of the equator, and are parallel to each other.

lee
the side of an object that is shielded from the wind.

lithosphere
the outer solid portion of the planet earth, made up of the earth's crust and upper mantle. All the rock on earth.