Latent Heat - The heat that is either absorbed or released when a substance undergoes a change of state. In weather, latent heat is an important factor when water changes state between liquid, solid, and vapor. For example, when water goes from vapor to liquid, latent heat is released into the atmosphere. The release of heat during condensation is one of the main energy sources for hurricanes.

Fujita Scale or F-Rating - A scale that uses visual damage to determine the strength of a tornado. The Fujita scale was developed by Dr. Fujita in 1971 while he was conducting research at the University of Chicago. The scale goes from 0 to 5, with 0 being weak and 5 being violent. The Fujita scale was decommissioned in the US in 2007 because it didn't fully account for different structural types. The enhanced Fujita scale is now being used to rate tornadoes.

Lake Effect Snow - The driving force behind lake effect snow is arctic air moving over relatively warm lake water. When this occurs, moisture and warmth is transferred out of the lake and into the lower levels of the atmosphere. When the moistened air reaches the shore, the air rises, inducing bands of snow. Snowfall rates in heavier lake effect snow bands can be as high as 3-6 inches per hour, causing near white-out conditions.

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.

Bow-Echo - The radar representation of a microburst or downburst, seen as a line of storms morphing from a straight line to an outwardly curved arc. Bow echoes mark the leading edge of damaging straight-line winds which can gust to over 100 mph in some cases.

Pyranometer - An instrument that is used to measure the sun's energy, know as solar radiation. It was invented in 1893 by a Swedish meteorologist named Anders Knutsson Angstrom. This was the first instrument that could measure both direct and indirect solar radiation.

Radiation Fog - This type of fog forms at night under clear skies with calm winds. Under these conditions heat that was absorbed by the earth's surface during the day is allowed to radiate back into space. As the earth's surface continues to cool, provided a deep enough layer of moist air is present near the ground, the humidity will reach 100% and fog will form. Radiation fog varies in depth from 3 feet to about 1,000 feet and is always found at ground level and usually remains stationary. This type of fog can reduce visibility to near zero at times and make driving very hazardous.