Indian summer
An unseasonably warm spell with clear skies near the middle of autumn. Usually follows a substantial period of cool weather.
Inversion
An increase in air temperature with height.
Land breeze
A coastal breeze that blows from land to sea, usually at night.
Lenticular cloud
A cloud in the shape of a lens. This type of cloud can often be seen forming a cap over Mount Rainier.
Marine climate
A climate dominated by the ocean, because of the moderating effect of water, sites having this climate are considered relatively mild.
Maritime air mass
An air mass that originates over the ocean. These air masses are relatively humid.
Maritime polar air
Cool, humid air mass that forms over the cold ocean waters of the North Pacific and North Atlantic.
Offshore flow (or wind or breeze)
A breeze that blows from the land out over the water. Opposite of an onshore breeze. This condition results in warm, dry weather conditions for Western Washington.
Onshore flow (or wind or breeze)
A breeze that blows from the water onto the land. Opposite of an offshore breeze. Sometimes referred to as a "marine push."
Prevailing wind
The wind direction most frequently observed during a given period.
Radar
An instrument useful for remote sensing of meteorological phenomena. It operates by sending radio waves and monitoring those returned by such reflecting objects as raindrops within clouds.
Rain Shadow
The region on the leeside of a mountain where the precipitation is noticeable less than on the windward side. The occurs on the eastern sides of both the Olympic and the Cascade Mountain Ranges.
Sea breeze
A coastal local wind that blows from the ocean onto the land. The leading edge of the breeze is termed a sea breeze front.
Storm surge
An abnormal rise of the sea along a shore. Primarily due to the winds of a storm over the ocean.
Temperature inversion
An extremely stable air layer in which temperature increases with altitude, the inverse of the usual temperature profile in the troposphere.
Thermal
A small, rising parcel of warm air produced when the earth's surface is heated unevenly.
Upslope fog
Fog formed as moist, stable air flows upward over a topographic barrier.
Visibility
The greatest distance an observer can see and identify prominent objects.
Wind-chill factor
The cooling effect of any combination of temperature and wind, expressed as the loss of body heat. Also called wind-chill index.
