Black ice - A thin coating of clear ice that can form on roadways. It is most common during the winter season and is called black ice because the dark road surface can be seen through it.

Computer Model - A system of computers which run complex physics equations on meteorological data to produce mathematical forecasts. Forecast models are first initialized with the current conditions in the atmosphere, and then thru a series of complex algorithms, they model what will be happening anywhere from 12 to 180 hours from the current time. There are several computer models that meteorologists utilize in predicting the weather.

Polar Vortex - The polar vortex is an area of low pressure that coincides with the pool of arctic air that encircles the North or South Pole. Each fall, the polar vortex begins to form due to decreasing daylight near the poles. By mid-winter it becomes more influential to the weather patterns in the mid-latitudes.

Tornado - A violently rotating column of air that reaches the ground from the bottom of a severe thunderstorm. Tornadoes become visible due to clouds associated with them as well as the dust and debris that get sucked into them. The US sees more tornadoes than any country in the world as around 1,200 can be expected each year.

Isotach - A line of equal wind speed on a weather map. The most common use for isotachs is finding the location of upper level jet streams and jet streaks. For example, the polar jet stream in the northern hemisphere is located by analysing isotachs at around 30,000 ft. Isotachs in the polar jet stream can indicate winds speeds of over 200 mph at times.

Insolation - Insolation is the amount of solar radiation that reaches the earth and the atmosphere. The amount of insolation at a specific location varies due to the length of day and the angle of the sun. During the winter in the northern hemisphere, the shorter days compiled with the lower angle of the sun results in much lower insolation compared to what is received during the summer months.

Saffir-Simpson Scale - The scale that rates the strength of a hurricane based on its peak 1 minute sustained wind speeds. The scale goes from 1 to 5 with 5 being the strongest. When a tropical storm's wind speeds reach 74 mph or higher it becomes a category 1 hurricane. A category 5 hurricane has sustained winds of 157 mph or greater.