Weather Glossary – L


LAND BREEZE – A wind that blows from the land towards a body of water. Also known as an offshore breeze.

LA NINA – The opposite of El Nino, when a major cooling occurs in the equatorial waters in the Pacific Ocean which is characterized by shifts in “normal” weather patterns.

LAPSE RATE The change in temperature with altitude in the atmosphere.

LATENT HEAT – the heat energy that must be absorbed when a substance changes from solid to liquid and liquid to gas, and which is released when a gas condenses and a liquid solidifies.

LEE TROUGH– Low pressure which develops just east of the Rocky Mountains or Cascades. Often lee troughs become organized into mature cyclones as they develop eastward.

LIFTED INDEX– The environmental temperature at 500 millibars minus the 500 millibar parcel temperature on a Skew-T diagram. Negative LI values are unstable.

LIGHTNING An electrical discharge from a thunderstorm.

LIKELY – In probability of precipitation statements, the equivalent of a 60 or 70 percent chance.

LLJ– Low Level Jet. Strong Planetary Boundary Layer winds which advect warmer temperatures and moisture into the forecast area.

LOW- The center of an area of low pressure, accompanied by cyclonic and inward wind flow in the northern hemisphere. Also known as a cyclone.