Suspended particles in the atmosphere which range in size from about
10-3 µm to 20 µm. Volcanoes, car exhaust, industrial
plants, forest fires, and even ocean evaporation fill the Earth's atmosphere
with not only gaseous pollutants, but also very small particles. These
particles, which include dust, ash, spores, bacteria, viruses, ammonia, organic
material, sea salt crystals, and sulfur and nitrogen compounds, clump together
with gases and water in the atmosphere to form aerosols.
albedo
The albedo is a measure of the reflective quality of a surface. Albedo is
the ratio of the amount of light striking a surface to the amount reflected
from the surface and is typically given as a percent. A surface having an
albedo of 50% would reflect half of the light reaching it, whereas an albedo of
0% would indicate that no sunlight is reflected. Dry sand reflects
approximately 35% of the sunlight that strikes its surface. Fresh snow reflects
approximately 85%.
algorithm
A precise rule (or set of rules) specifying how to solve some problem.
altitude
Vertical distance above sea-level or the earth's surface.
The "envelope" of air and gases surrounding the Earth that bound
to it by gravity. The layers of the atmosphere typically extend up to about 350
kilometers or 217 miles above the Earth's surface.
atmospheric haze
Fine dust or water vapor causing the lack of transparency of the air.
A colorless, odorless gas that is a major greenhouse gas. Commercially,
carbon dioxide is used as a refrigerant (dry ice), in beverage carbonation,
and in fire extinguishers
carbon monoxide (CO)
A gas produced by the incomplete combustion
of fossil fuels (gas, oil, or coal), engines or open fires, oil
burners, gas fires, and water heaters.
A method of measuring temperature named after Anders Celsius, a Swedish
astronomer, who invented it. Water freezes at 0 degrees C and boils at 100
degrees C.
Acronym for Clouds and the Earth's Radiant Energy System. An instrument
onboard the TRMM, Terra, and Aqua satellites which measures the Earth's
radiation budget.
chlorofluorocarbon (CFC)
Gases made of chlorine, fluorine, and carbon. In the troposphere, a CFC
molecule does not normally react with other substances. However, in the
stratosphere, ultraviolet radiation breaks apart the CFC molecule releasing a
chlorine atom which catalytically destroys many ozone molecules.
The simplest type of volcano built from particles of congealed lava ejected
from a single vent. Most cinder cones have a bowl-shaped crater at the summit
and rarely rise more that a thousand feet or so above the surroundings.
A type of volcano built by the accumulation of materials erupted through
the conduit, which increases in size as lava, cinder, and ash are added to
its slopes.
Aerosols comprising minerals from arid and semi-arid regions that absorb
sunlight as well as scatter sunlight. Through absorption of sunlight, the dust
particles warm the layer of the atmosphere where they reside. This warmer air
is believed to inhibit the formation of storm clouds. Desert dust is also a
source of nutrients for many remote regions.
The NASA Langley Atmospheric Science Data Center was established in 1991
to support the Earth Observing System as part of NASA's Earth Science
Enterprise (formerly known as Mission to Planet Earth), and is one of
several Distributed Active Archive Centers sponsored by NASA as part of the
Earth Observing System Data and Information System (EOSDIS).
Type of energy distinct from chemical energy, kinetic energy, etc.
Visible light and radio waves are both forms of electromagnetic energy. See
also "Radiation."
electromagnetic radiation
Radiation consisting of waves of energy associated with electric and
magnetic fields.
acronym for Earth Radiation Budget Satellite. A NASA satellite carrying
instruments used in the ERBE experiment to study the radiation budget and
atmospheric aerosols and gases.
The greenhouse effect is a naturally occurring process that aids in heating
the Earth's surface and atmosphere. It results from the fact that certain
atmospheric gases absorb longwave radiation from the Earth's surface. Without
the greenhouse effect, life on this planet would probably not exist as the
average temperature of the Earth would be a chilly -18 degrees Celsius, rather
than the present 15 degrees Celsius.
Human activities, such as the burning of fossil fuels and vegetation and
the alteration of natural surface cover, generate aerosols. Averaged over the
globe, aerosols made by human activities are currently estimated to account for
about 10 percent of the total amount of aerosols in our atmosphere. The
concentration of aerosols is highest in the northern hemisphere where
industrial activity is centered.
hydrocarbon
An organic compound made of the elements hydrogen and carbon.
Examples: methane CH4, propane C3H8.
Of or relating to the range of invisible radiation wavelengths from about
750 nanometers, just longer than red in the visible spectrum, to 1 millimeter,
on the border of the microwave region.
The part of the atmosphere, between the mesosphere and exosphere.
Sufficient quantities of ions and free electrons exist to reflect and/or
refract electromagnetic waves.
acronym for National Aeronautics and Space Administration
nitrous oxide
Produced biologically in oceans and soil. Activities by humans such as
vehicle exhausts, biomass burning, industrial combustion, and chemical
fertilizers produce nitrous oxides. Nitrous oxide is also used as a mild
anesthetic in dentistry and surgery commonly know as "laughing
gas".
acronym for National Oceanic and Atmospheric Administration. Two NOAA
satellites (in addition to the ERBS satellite) that carried ERBE instruments
were NOAA-9 and NOAA-10.
Gives a broad field of view fixed on a point directly below the
satellite. ERBE's nonscanning instruments contained 5 detectors which measure
radiation reflected and emitted by the Earth-atmosphere system.
A measure of the visual or optical thickness; a measure of how opaque a
medium or the atmosphere is to radiation passing through it. It is not measured
in meters or feet; but is nondimensional. An optical depth below 3 is
considered to be optically thin; above 10 is considered optically thick
ozone
A molecule made up of three atoms of oxygen. In the stratosphere, ozone
occurs naturally and provides a protective layer shielding the Earth from
ultraviolet radiation, and the subsequently harmful health effects on humans
and the environment. In the troposphere, ozone is a chemical oxidant and a
major component of smog. Ozone is an effective greenhouse gas especially in
the middle and upper troposphere and lower stratosphere.
Energy in the form of electromagnetic waves. Various forms of radiation
have different characteristics, depending on the wavelength. (see
"shortwave radiation" and "longwave radiation.")
acronym for Stratospheric Aerosol and Gas Experiment. A multi-generation
NASA mission to study aerosols and atmospheric chemistry.
SAGE I
Stratospheric Aerosol and Gas Experiment I. SAGE I collected data for 3
years, from 1979 through 1981.
SAGE II
The SAGE II experiment measures the amount of ozone and other trace gases
in the atmosphere by measuring the amount of sunlight that comes through the
atmosphere at different altitudes. SAGE II instrument was launched onboard the
ERBS spacecraft in 1984 and has collected data for over 15 years.
SAGE III
The SAGE III instrument was launched aboard a Russian Meteor-3M platform in
December 2001.
A type of volcano built almost entirely of fluid lava flow with a
dome-like, warrior's shield, or a plateau shape. The largest shield volcano
is Mauna Loa. It makes half of the area of the island of Hawaii and began to
form nearly a million years ago.
shortwave radiation
Radiation with higher energy and thus a shorter wavelength than heat. An
example of shortwave radiation is sunlight.
solar radiation
The total electromagnetic radiation emitted by the sun.
Layer of the atmosphere between the troposphere and the mesosphere,
extending from about 18 to 50 kilometers (12 to 30 miles) above the earth's
surface.
sulfur dioxide (SO2)
A heavy toxic gas that is easily condensed to a colorless liquid and
is a major air pollutant. Certain large volcanic eruptions are thought to
release enough aerosols in the form of sulfur dioxide to cool the climate.
The flagship of NASA's Earth Observing System (EOS), Terra is collecting a
new global data set to enable research into the ways that Earth's land, oceans,
atmosphere, ice, radiant energy, and life function as a whole system.
Tropical Rainfall Measuring Mission. Satellite launched by Japan and the
United States to study rainfall and its relationship to the release of
energy.
tropics
The area bounded by the Tropic of Cancer, 23.5° lat N, on the north and
Tropic of Capricorn, 23.5° lat S, on the south is known as the
"tropics."
The lowest atmospheric layer, between the Earth's surface and the
tropopause. The troposphere is the region of most interest to meteorologists
because the Earth's weather occurs in this atmospheric layer.
Aerosols released during volcanic eruptions, notably ash, soot, and sulfur
dioxide (SO2). These aerosols reflect sunlight, reducing the amount
of energy reaching the lower atmosphere and the Earth's surface, cooling them.
Volcanic Explosivity Index
An eruption magnitude scale called the Volcanic Explosivity Index, or VEI,
used to measure the strength of volcanic eruption. Volume of products,
eruption cloud height and qualitative observations are used to determine the
explosivity value. The scale ranges from 0 (small non-explosive eruptions) to 7
(large explosive eruptions).
In radiation, the distance between periodic spatial repetitions of an
electromagnetic wave at a given instant of time; used extensively to classify
the nature of the radiation, since most of the interactions between radiation
and matter are extremely sensitive to the wavelength of the radiation.
The state of the atmosphere, mainly with respect to its effects upon life
and human activities. As distinguished from climate, weather consists of
short-term (minutes to days) variations in the atmosphere. Popularly, weather
is thought of in terms of temperature, humidity, precipitation, cloudiness,
visibility, and wind.
