Zodiacal Light - A softly luminous cone of white light visible from an hour or so after sunset or before dawn. The cause of this pre-dawn or post-dusk light is created by sunlight that reflects off of grains of dust in space between the Earth and the Sun. To an unknowing observer it can be mistaken for a glare of city lights on the distant horizon.

Isotherm - A line on a weather map joining locations of equal temperature. When looking at weather maps displaying temperatures across the lower 48, isotherms are used to divide the country in different colors based on the varied temperatures. Oftentimes, each isotherm will indicate a change of 5 or 10 degrees.

Microburst - A strong and localized downdraft that occurs beneath a strong to severe thunderstorm. Microburst's occur on a small scale, as most are smaller than a mile wide in diameter. These localized, intense winds can produce major damage and typically last for a matter of seconds to several minutes.

Hook Echo - A distinctive radar pattern that has the appearance of a hook extending from the radar echo. A hook echo indicates that the thunderstorm's updraft is rotating. This rotating updraft is called a mesoscyclone. These types of thunderstorms are called supercells and present the greatest risk for tornadic activity.

Ice Fog - This type of fog forms when the air temperature is well below freezing and it's composed entirely of tiny ice crystals that are suspended in the air. Ice fog will only be witnessed while in the midst of an arctic air mass. Generally, the temperature needs to be 14F or colder in order for ice fog to form.

Sub-vortices - Small areas of intense rotation located within a type of tornado called a multi-vortex tornado. These spinning whirls can be thought of as individual tornadoes that are mixed within the main tornado. These are also sometimes referred to as suction vortices and the winds within them can be 100 mph stronger than the main body of the tornado. These can explain why the damage path in a tornado can vary greatly.

Cumulonimbus - A form of a cumulus cloud that grows vertically to great heights. These clouds are associated with heavy thunderstorm activity and are the result of strong currents of rising air called updrafts.