Contrail - A contrail is the condensation trail that is left behind by a passing jet plane or rocket. Contrails form when hot humid air from jet exhaust mixes with ambient air that is colder and drier. Contrails are composed of water droplets, and can therefore be thought of as a man-made cloud streak.

Evaporation or Mixing Fog - This type of fog forms when sufficient water vapor is added to the air by evaporation, and the moist air mixes with relatively drier air. The two common types are steam fog and frontal fog. Steam fog forms when cold air moves over warm water. This type of fog takes on the appearance of wisps of smoke rising off the surface of the water. The other type of evaporation fog is known as frontal fog. This type of fog forms when warm raindrops evaporate in a cool air mass near the ground.

Thunderstorm - A local storm that spawns from a cumulonimbus cloud and is accompanied by lightning and thunder. The atmospheric conditions needed to produce a thunderstorm are warm and moist conditions in the low levels. It is estimated that around 1,800 thunderstorms are occurring on Earth at any given moment.

Synoptic Scale - In meteorology this refers to the study of large scale systems that develop in the atmosphere. Major cyclones and their associated fronts are a commonly studied feature in synoptic meteorology. In order to be on the synoptic scale, a system must stretch across a distance of at least 600 miles.

NAM (North American Mesoscale) - This is one of the preferred short range forecast models that are run in the US at the National Centers for Environmental Prediction in College Park, MD. The model runs four times per day, with each cycle running out to 84 hours.

Wiresonde - An atmospheric sounding instrument that is attached to a weather balloon and is used to obtain temperature and humidity information between ground level and a height of a few thousand feet above the surface.

Black Blizzard - The name commonly given to dust storms that occurred in the Great Plains of North America during the Dust Bowl days of the 1930s. At times these black blizzards would originate in an area such as western Kansas and then travel all the way to the east coast.