Definitions of Additional Weather Terms
Climates-Atmospheric and weather conditions in a particular area over a long
period of time
Convection-A pattern of air flow established due to a difference (gradient)
of temperatures. Use of the term in meteorology indicates a pattern of air
flow due to differences in temperature with altitude
Coriolis-A circular and spiral spin of air in response to a pressure system.
The spin is clockwise in the Northern hemisphere with a high pressure
system and counterclockwise with a low pressure system.
Doldrums-An area located at the equator where Northerly and Southerly
winds converge. Often this area has very little wind or air flow.
Weight of air at sea level- At sea level and at 15°C according to ISA
(International Standard Atmosphere), air has a density of approximately
1.22521 kg/m3.
Freezing Point-The freezing point of water is 0oC or 32oF under normal
conditions.
Tornado- A tornado (often referred to as a twister or, erroneously, a
cyclone) is a violent, dangerous, rotating column of air that is in contact with
both the surface of the earth and a cumulonimbus cloud or, in rare cases,
the base of a cumulus cloud. A tornado is "a violently rotating column of air,
in contact with the ground, either pendant from a cumuliform cloud or
underneath a cumuliform cloud, and often (but not always) visible as a funnel
cloud". For a vortex to be classified as a tornado, it must be in contact with
both the ground and the cloud base. Scientists have not yet created a
complete definition of the word; for example, there is disagreement as to
whether separate touchdowns of the same funnel constitute separate
tornadoes. Tornado refers to the vortex of wind, not the condensation
cloud.
Hurricane- A tropical cyclone is a storm system characterized by a large
low-pressure center and numerous thunderstorms that produce strong winds
and heavy rain. Tropical cyclones strengthen when water evaporated from
the ocean is released as the saturated air rises, resulting in condensation of
water vapor contained in the moist air. They are fueled by a different heat
mechanism than other cyclonic windstorms such as nor'easters, European
windstorms, and polar lows. The characteristic that separates tropical
cyclones from other cyclonic systems is that at any height in the
atmosphere, the center of a tropical cyclone will be warmer than its
surrounds; a phenomenon called "warm core" storm systems. The term
"tropical" refers to both the geographic origin of these systems, which form
almost exclusively in tropical regions of the globe, and their formation in
maritime tropical air masses. The term "cyclone" refers to such storms'
cyclonic nature, with counterclockwise rotation in the Northern Hemisphere
and clockwise rotation in the Southern Hemisphere. The opposite direction
of spin is a result of the Coriolis force. Depending on its location and
strength, a tropical cyclone is referred to by names such as hurricane,
typhoon, tropical storm, cyclonic storm, tropical depression, and simply
cyclone.
Tsunami- A tsunami, also called a tsunami wave train, and at one time
incorrectly referred to as a tidal wave, is a series of water waves caused by
the displacement of a large volume of a body of water, usually an ocean,
though it can occur in large lakes. Tsunamis are a frequent occurrence in
Japan; approximately 195 events have been recorded. Owing to the immense
volumes of water and the high energy involved, tsunamis can devastate
coastal regions. Earthquakes, volcanic), landslides and other mass
movements, meteorite ocean impacts or similar impact events, and other
disturbances above or below water all have the potential to generate a
tsunami eruptions and other underwater explosions (including detonations of
underwater nuclear devices.
Isobar-A line on a weather map indicating the same barometric pressure
along the line.
Isotherm-A line on a weather map indicating the same temperature along the
line.
Dew Point- The dew point is the temperature to which a given parcel of
humid air must be cooled, at constant barometric pressure, for water vapor
to condense into water. The condensed water is called dew. The dew point is
a saturation temperature. The dew point is associated with relative
humidity. A high relative humidity indicates that the dew point is closer to
the current air temperature. Relative humidity of 100% indicates the dew
point is equal to the current temperature and the air is maximally saturated
with water. When the dew point remains constant and temperature
increases, relative humidity will decrease.
CFC’s-An acronym for chlorofluorocarbons which are/were used for
propellants, refrigerants, and foaming agents. Some CFC’s are atmospheric
pollutants causing depletion of ozone in the stratosphere.
Leaded Gasoline-Gasoline previously contained (completely banned in 1995) a
lead compound (tetraethyl lead) that was used as an anti-knocking agent in
automobiles and other internal combustion engines. The lead released by
automotive exhaust or from other internal combustion engines was a major
environmental pollutant and accumulated in biological food chains.