A natural climate variation in which the trade winds are stronger than normal and surface water off of South America is cold.
lahar
A volcanic mudflow containing ash, rock, and water from melting snow or rainfall that races down river valleys during an eruption.
lake
A large body of freshwater drained by a stream; naturally occurring or human-made.
lake-effect snow
Extreme snowfall caused by the evaporation of relatively warm, moist air into a cold front that then drops its snow on the leeward side of the lake.
land breeze
A wind that blows from land to sea in winter when the ocean is warmer than the land.
landform
A physical feature that is part of the landscape, such as a hill or peninsula.
landslide
Rapid movement downslope of rock and debris under the influence of gravity.
latent heat
Energy absorbed or released as material changes from solid to liquid or liquid to gas.
lateral continuity
A sedimentary rock layer that extends sideways as wide as the basin in which it forms.
lateral moraine
Glacial till formed from debris that falls at the edges of a glacier.
laterite
Nutrient poor, red, tropical soil that forms in rainforest areas.
latitude
The location of a place between the north and south pole relative to the equator.
lava
Molten rock that has reached the Earth’s surface.
lava dome
A dome-shaped plug of viscous lava that cools near the vent of a volcano.
lava plateau
A flat area formed by the eruption of large amounts of fluid lava.
law of conservation of energy
Law stating that energy cannot be created or destroyed.
leaching
The process of removing dissolved minerals as they are carried to lower layers in soil.
leaf litter
Dead leaves, branches, bark, and other plant parts that accumulate on the floor of a forest.
levee
A raised structure designed to hold back the waters of a stream or river in the case of a flood.
light-year
The distance light can travel in one year; 9.5 trillion kilometers.
lightning
A huge discharge of electricity typical of thunderstorms.
limiting factor
The one factor that limits the population of a region. The limiting factor can be a nutrient, water, space, or any other biotic or abiotic factor that the species need.
limnology
The study of freshwater bodies and the organisms that live in them.
liquefacation
Clay, silt, and sand saturated with water become like quicksand, lose their strength, and behave more like a liquid than a solid.
lithification
The creation of rock from sediments.
lithosphere
The layer of solid, brittle rock that makes up the Earth’s surface; the crust and the uppermost mantle.
loam
Soil texture that forms from a roughly equal combination of sand, silt and clay.
location
Where an object is on Earth, best described in three dimensions.
loess
Extremely fine-grained, wind-borne deposit of silts and clays; forms nearly vertical cliffs.
longitude
The location of a place relative to the Prime Meridian, which runs north-south through Greenwich, England.
longshore current
Local surface currents that move along a shoreline in the direction of prevailing winds.
low Earth orbit
Satellites that orbit relatively close to Earth.
low pressure zone
A region where relatively warm, lower density air is rising.
low tide
The lowest water levels during a day when high tide is one-quarter of the way around Earth’s sphere.
LUCA (Last Universal Common Ancestor)
The last life form that was the ancestor to all life that came afterward
lunar
Related to the Moon.
lunar eclipse
An eclipse that occurs when the Moon moves through the shadow of the Earth and is blocked from view.
luster
The way light reflects off of the surface of the mineral.