Karaburan - During the spring and summer in central Asia, this violent northeast wind blows in clouds of dust thick enough to darken the sky.
Katabatic Wind - In times of light large-scale winds, this wind flowing down a mountain slope may form due to cooling at the surface. The slope cools a vertical section of the air above it from the slope surface as high as 130 to over 1300 feet, and this vertical section of air is colder than that overlying the valley below, resulting in a wind blowing down the mountain slope.
Kaus - A wind from the southeast in the Persian Gulf which ranges from moderate to gale force and brings clouds, rain and squalls.
Kelvin Temperature Scale - An absolute temperature scale on which 0 is the point at which all molecular motion stops.
Killing Freeze - A condition which occurs when the air temperature falls below 32 degrees Fahrenheit and vegetation is killed withoute the formation of frost crystals.
Knik Wind - A wind of the Matanuska Valley in Alaska blowing from the southeast and most frequent in winter when it can cause pronounced rises in temperature.
Kona - A southwest or south-southwest rain-bearing wind in Hawaii. It blows on the southwest slopes lying to the lee of the northeast trade winds; thus, the name Kona, meaning "leeward".
Krakatoa (or Krakatau) Winds - An easterly wind layer between about 11 and 15 miles above the earth in the Tropics. The name comes from the observed movement of the volcanic dust from the explosion of Krakatoa Volcano in 1883 (see the Volcano Weather page of this website).
Meteoprological Kytoon, 1967 from NOAA Photo Library
Kytoon - A captive ballon which is used to keep meteorological instruments aloft at approximately a constant height.
Labbe - A mild, humid and rather strong southwest wind in southeastern France. It occurs in March and brings clouds and sometimes rain.
Lake Breeze - A wind similar to the sea breeze blowing from a large lake onto the shore during the afternoon. It is caused by the difference in surface temperature between the water and the land.
Lake Effect - The modifying effect of a lake on the weather near its shore and downwind. Also, it may refer to the enhanced precipitation which falls downwind of a large lake.
Lake-effect Snow - Localized bands of snow which fall on the leeward side of lakes when relatively cold air passes over the warmer lake waters.
Lambing Storm - A light snowfall in England during spring.
La Nina - A cooling of the ocean waters in the equatorial Pacific Ocean and the opposite of El Nino.
Land Breeze - A breeze which blows from the land to the sea (or to a large lake) when the sea or lake surface is warmer than the nearby land. It usually blows at night and is the counterpart to the sea breeze.
Lapse Rate - Change in temperature with height in the atmosphere.
Latent Heat of Condensation - When liquid water evaporates into water vapor, heat is absorbed, as evaporation is a cooling process. However, when water vapor condenses into clouds, this stored, or latent heat, is then released and is called the latent heat of condensation.
Leader - The initial electrical discharge which begins each return stroke of a cloud-to-ground lightning flash.
Lee Trough - A low pressure trough which forms on the lee side of a mountain range.
Levante - The Spanish term applied to an east or northeast wind blowing along and inland from the coast of southern France to the Straits of Gibraltar mostly between February and May and October and December.
Libeccio - The Italian name for the southwest wind and particularly used in northern Corsica for the west and southwest wind all year but especially during the winter when that wind is frequently stormy.
High power Doppler Lidar - photo from NOAA.
Lidar - A word which stands for light detection and ranging. This instrument, of which there are several kinds, uses a transmitter with a pulsed laser beam and a receiver, which is usually a telescope, having an electronic signal processing unit for the purpose (meteorologically) of detection and ranging of distant atmospheric targets.
Lifted Index - This index, often abbreviated LI, is a measurement of the instability in the atmosphere. It is obtained by computing what the air temperature near the ground would be if it were lifted to a higher altitude (often 18,000 feet) and then compaing that temperature with the actual air temperature at that altitude. If the value comes out negative, it indicates instability in the air, and the greater the negative value, the more unstable the air mass.
Lightning - An electrical discharge from a thunderstorm.
Lightning Channel - The path through the air along which a lightning discharge takes place.
Lightning Discharge - The combined series of electrical processes taking place within about one second and which result in a transfer of charge along a discharge channel between areas of opposite electrical charge either within a cumulonimbus cloud, between cumulonimbus clouds, between a cumulonimbus cloud and the air, or between the cumulonimbus cloud and the ground.
Lightning Echo - A radar echo which is caused by lightning.
Lightning Flash - The total observed lightning discharge which usually has a number of seperate lightning strokes within it and lasts usually less than one second.
Lightning Stroke - A leader and its return stroke. Within one lightning flash, there are usually between 3 and 4 distinct lightning strokes in the same lightning channel occurring so rapidly that the human eye cannot distinguish between them. There may be more lightning strokes within one flash, and if a lightning flash appears to flicker, the flickering effect is caused by the seperate lightning strokes within that flash.
Lithometeor - A general term used to describe dry substances such as dust, haze, sand and smoke suspended in the atmosphere.
Little Ice Age - A term applied to a period between approximately either 1550 and 1850 or as early as 1300 to 1850 during which time glaciers, especially in the Northern Hemisphere advanced. During much of this period sunspot activity was at a low point, and summers were no longer so warm as they had been.
Lombarde - A wind blowing from the east (from Lombardy) which comes from the high Alps and is frequent along the border between France and Italy. During winter, the lombarde is quite violent in the mountains, but on the plains it is quite gentle and dry.
Looming - A type of mirage in which objects far away and often below the horizon appear above the horizon.
Low - An area of low atmospheric pressure with cyclonic circulation, and thus a cyclone.
Low-level Jet - A jet stream usually located in the lower one or two miles of the troposphere.
Lunar Rainbow - A rainbow formed by the light of the moon rather than the sun.