A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z
- A -
Anemometer: An instrument that measures wind.
Anticyclone: High pressure area; generally referred to as a "High".
Anticyclone: Circulation The movement of air around a High pressure center; clockwise in the Northern Hemisphere, counterclockwise in the Southern Hemisphere.
Atmospheric Pressure: The weight of the atmosphere, in force per unit area.
- B -
Backing: A counterclockwise change in wind direction; for instance, from the Southeast to East to Northeast.
Barometer: An instrument for measuring atmospheric pressure.
Building: Intensification of High pressure systems applied to a Ridge or High pressure center.
- C -
Central Pressure: The atmospheric pressure at the center of a High or Low; the highest pressure of a High; the lowest pressure of a Low.
Circulation: In the broadest sense, an organized movement of air.
Coastal Forecast: A forecast of wind and wave conditions between the coastline and 100 miles offshore.
Cold Front: The boundary between a cold air mass that is advancing, and a relatively warmer air mass. Generally, characterized by steady precipitation followed by showery precipitation.
Cut-off Low: A Low pressure system which has been displaced out of the basic Westerly current and lies to the South of its current.
Cyclone: A Low pressure area, generally referred to as a "Low". Most cyclones are not accompanied by violent storms. Hurricanes and Typhoons are intense "Lows" or cyclones.
Cyclonic Circulation: The movement of air around a Low pressure center; counterclockwise in the Northern Hemisphere, clockwise in the Southern Hemisphere.
Top- D -
Deepening: A decrease in the central pressure of a cyclone. Deepening is usually accompanied by an increase in wind speeds and by worsening weather.
Downburst: A severe localized downdraft from a thunderstorm.
- E -
Easterlies: Any winds with components from the East, but usually applied to broad currents of persistent Easterly winds. The tropical Easterlies, sometimes referred to as the Trades, dominate the area surrounding the Hawaiian Islands.
El Nino: A major warming of the Equatorial waters in the Pacific Ocean. El Nino events occur every 3-7 years, and are characterized by shifts in "normal" weather patterns.
Extra-tropical Cyclone: A cyclonic storm that is not of tropical origin. The term usually refers to Lows of middle and higher latitudes. Tropical cyclones can undergo transition and become extra-tropical as they move into the middle and higher latitudes.
- F -
Fastest Mile: The fastest speed, in miles per hour, of any "mile" of wind.
Filling: An increase in the central pressure of a cyclone. Filling is usually accompanied by a weakening of the cyclonic circulation, a decrease in wind speeds, and improving weather.
Front: The transition zone between air masses. A front almost invariably separates air masses of different temperature. Features which may indicate a front include a pressure trough, a change in wind direction, a change in moisture content of the air, and certain characteristic cloud and precipitation forms.
- G -
Gale: Wind speeds from 39 to 54 mph (43 to 47 knots).
Gradient: The rate of decrease of a meteorological element, such as temperature or pressure, as measured in the direction in which the decrease is greatest.
Gust: A sudden brief increase in the speed of the wind.
- H -
Height (falls/rises): Changes in the height of constant pressure surfaces, equivalent to falling or rising pressure at that height.
High: An area of relatively high atmospheric pressure surrounded by lower pressure.
High Wind: Sustained winds of 40 mph or more and or gusts of 58 mph or more.
- I -
Isobar: On a weather map, a line connecting points of equal pressure.
- J -
Jet Stream: A meandering and relatively narrow belt of strong winds (speeds of 50 knots or more) embedded in the normal wind flow aloft; generally found at high altitudes.
- K -
Knot: One nautical mile per hour (1.15 mph).
Kona: A stormy, rain-bearing wind from the Southwest or SSW in Hawaii. It blows about five times a year on the SW slopes, which are in the lee of the prevailing NE trade winds (Kona is a Polynesian word meaning "leeward").
Kona Wind: A wind from the South or South West.
- L -
Land Breeze: A coastal breeze blowing from land to sea. It usually occurs at night and alternates with a sea breeze which blows in the opposite direction during the day.
Leeward: In Hawaii, those areas protected from the trade winds (dry side). Light and Variable Wind speeds of less than 5 mph with no discernible direction.
Low: An area of relatively low atmospheric pressure in the upper atmosphere and not associated with a Low near sea level.
- M -
Microburst: A strong localized downdraft from a thunderstorm.
Millibar: A unit of atmospheric pressure, normal surface pressure is approximately 1013 millibars (29.92 inches of mercury).
MPH: Miles per hour
- N -
Nexrad: Next generation radar. A system of Doppler radars planned for nationwide installation.
- O -
Off-shore Breeze: A wind that blows from the land towards a body of water. Also known as a land breeze.
On-shore Breeze: A wind that blows from a body of waters towards the land. Also known as a sea breeze.
Orographic Uplift: The vertical forcing of air by terrain features such as hills or mountains. This can create orographic clouds and/or precipitation.
- P -
Pacific High: The semi-permanent subtropical High, centered normally at 30 degrees - 40 degrees North and 150 degrees West.
Peak Gust: Highest wind speed recorded in a 24 hour period at a weather observing station.
Polar Front: The frontal zone between air masses of polar and those of tropical origin.
Pressure: The force exerted by the interaction of the atmosphere and gravity. Also known as atmospheric pressure.
Prevailing Wind: The wind direction most frequently observed.
Prognostic Chart: A weather chart of expected future weather patterns and prediction.
- Q -
(empty)
- R -
Retrograde: The movement of an atmospheric wave or pressure system in a direction opposite to that of the basic flow in which it is embedded.
Ridge: A elongated area of relatively high pressure.
- S -
Sea Breeze: A coastal breeze blowing from sea to land. It usually occurs during the day and alternates with a land breeze, which blows in the opposite direction at night.
Sounding (upper Air): An observation of temperature, humidity, pressure, wind, etc., made through a vertical column of the atmosphere.
Storm Warning: A marine warning issued to denote wind speeds of 48-63 knots (55-74 mph).
Subsidence: A descending or "settling" motion of air, usually over a wide area. Subsiding air is generally stable.
Surface Pressure: The pressure exerted by the atmosphere at a given location on the Earth's surface.
Synoptic: Refers to the overall condition of the atmosphere at a given time.
- T -
Thunderstorm: Any time thunder is heard. May or may not be accompanied by precipitation and winds.
Tornado: An intensely rotating column of air in the shape of a funnel that extends from the base of a cumulonimbus cloud to the ground.
Trades: The prevailing winds in Hawaii are East - Northeast trades. In the Northern Hemisphere, the trade system, which covers most of the tropics, begins as North and NE winds at about latitude 30 degrees in January, and latitude 35 degrees in July, gradually turning to the NE and ENE as they approach the Equator. The trades are the most persistent wind system on Earth.
Tropical Cyclones: The general term for a cyclone, or Low, that originates over the tropical oceans. By international agreement tropical cyclones are classified according to their intensity as follows: tropical depression, winds less than 34 knots (39 mph);tropical storm, winds of 34 through 63 knots (39 through 73 mph); hurricane or typhoon, winds 64 knots (74 mph) and higher.
Tropopause: The boundary between the troposphere and the stratosphere, usually characterized by an abrupt decrease in lapse rate.
Trough: An elongated area of Low pressure.
Turbulence: Disrupted flow in the atmosphere characterized by gusts and eddies. Aircraft encounters with turbulence produces bumps and jumps in flights.
Typhoon: A hurricane occurring West of the International Dateline (180 degrees longitude).
- U -
(empty)
- V -
Veering: A clockwise change in wind direction; for instance, from Southwest to West to Northwest.
Vorticity: A measure of the amount of "spin" (or rotation) in the atmosphere.
- W -
Warning Forecast: Warning Forecast issued when a particular hazard is "imminent" or already occurring. Watch Forecast issued well in advance to alert the public of the possibility of a particular hazard.
Waterspout: A tornado occurring over water; rarely, a lesser whirlwind over water comparable in intensity to a dust devil over land.
Wind Advisories: Small Craft - 23-38 mph (20-33 knots)
Wind Classification (trades): Gentle - 8 to 12 mph (7-10 knots); Moderate - 13-18 mph (11-16 knots); Fresh - 19-24 mph (17-21 knots); Strong - 25-31 mph (22-27 knots); Near Gale - 32-38 mph (28-33 knots)
Wind Warnings: Gale - 39-54 (34-47 knots); Storm - 55-73 mph (48-63 knots); Hurricane - 74 mph (64 knots) and higher
Wind Direction: The direction from which the wind blows. Wind Shear The change of wind speed or direction with distance, usually vertical.
Wind Vane: An instrument that shows which way the wind is blowing.
Windward: In Hawaii, those areas exposed to trade winds (wet side).
- X -
(empty)
- Y -
(empty)
- Z -
(empty)
High Wind
Source(s):
National Weather Service
National Weather Service