Glossary of weather terms

Best Lifted Index is simply the most unstable (most negative) Lifted Index value found when checking different levels of the atmosphere.

Boundary clouds are low-level clouds that form close to the ground.

CAPE (180-0mb) means the calculation uses atmospheric pressure levels from 180 millibars down to the surface, which is where most thunderstorms form.

CAPE (255-0mb)** means the calculation uses atmospheric pressure levels from 255 millibars down to the surface.

CAPE (Convective Available Potential Energy) is a measure of the energy available in the atmosphere to create thunderstorms. Higher CAPE means a greater chance of severe weather like thunderstorms and tornadoes.

Celestial azimuth is the compass direction where the Sun or Moon rises or sets.

Celestial elevation is how high the Sun or Moon appears in the sky.

Convective clouds are formed when warm, moist air rises. They are often puffy or tall, like cumulus clouds.

Dew point is the measure of how much moisture is in the air. It is the temperature to which the air must be cooled for that water vapor to condense into liquid, like dew.

Low, middle and high clouds are categorized based on their typical altitude in the sky.

Moon phases are the different shapes of the Moon we see from Earth. These shapes change because as the Moon orbits Earth, we see varying amounts of its sunlit surface.

Precipitation rate is how fast rain, snow, sleet or hail is falling.

Pressure is the weight of the air pushing down on the Earth's surface. High pressure usually brings clear skies and calm weather. Low pressure often brings clouds, rain, or snow.

Radar reflectivity measures how much of a radar signal bounces back from precipitation. A stronger reflection usually means heavier rain or snow.

Relative humidity is a percentage that shows how close the air is to being completely full of moisture.

Sea Current Speed is how fast the surface water is moving horizontally in a particular direction.

Sea Current Streams are a way to show both the speed and direction of surface ocean currents.

Sea Salinity is the amount of dissolved salt in seawater

Sea Temperature is the temperature of the water at or very near the ocean's surface.

Significant Wave Direction tells you the direction the most important waves are traveling, whether they are swells or wind waves

Significant Wave Height is the vertical distance from the top of a wave to the bottom of a wave, specifically referring to the most important type of wave present, whether it's from wind or swell.

Significant Wave Period is the time it takes for two wave tops (crests) of the most important wave type (swell or wind wave) to pass a single point.

Snowfall rate is how fast new snow is piling up.

Swell 1, or primary swell, is typically the biggest and strongest swell, often coming from a large weather system like a storm.

Swell 2, or secondary swell, is a smaller and less dominant swell but can still affect sea conditions.

Swells are waves that originate from distant storms and are more organized and consistent than local wind waves. They can travel great distances and continue even after the storm that created them has gone.

Temperature is how hot or cold the air is.

The Lifted Index (LI) is a tool that helps meteorologists predict if thunderstorms and severe weather are likely. A negative LI means the air is unstable and thunderstorms are more likely, while a positive LI means the air is stable

Total cloud cover is the percentage of the sky covered by clouds.

Ultraviolet (UV) Index measures the strength of the sun's rays and your risk of getting a sunburn. The higher the number, the greater the risk.

Visibility is a measure of how far you can see.

Weather fronts are boundaries where two different air masses meet. A cold front is when cold air pushes out warm air, often bringing cooler weather and storms. A warm front is when warm air moves into cold air, usually causing temperatures to rise and light rain or fog.

Wind gust is a sudden, strong burst of wind.

Wind speed is how fast the air is moving.

Wind vector is a measurement that includes both the speed and direction of the wind.

Wind wave is a wave on the surface of water, like an ocean or lake, caused by wind blowing across it.