Blizzard Warning - Blizzard Warnings are issued when visibilities are reduced to a quarter mile or less for 3 hours or longer. Wind speeds must also be sustained at 35 mph with frequent higher gusts in order to achieve blizzard conditions.

Mirage - An optical effect created by the refraction of light caused by extreme temperature differences between the surface to just above it. The most common mirages look like pools of water in the distance over hot sand or pavement.

Rawinsonde - An instrument attached to a weather balloon that measures atmospheric pressure, temperature, humidity, and wind speed/direction at different layers of the atmosphere. As the instrument rises through the atmosphere, the data is sent via radio waves to a receiver on the ground. Rawinsondes are launched all over the world at specified times. The data from these launches is used in initializing the numerous forecast models.

Cloud - Any visible mass of water droplets, ice crystals, or a mix of both that become suspended in the atmosphere. Fog is a cloud that forms at the ground, while cirrus clouds oftentimes form at around 40,000 feet.

G.O.E.S. - An acronym that stands for Geostationary Operational Environmental Satellite. A geostationary satellite remains fixed over a specific area of the globe at an altitude of around 22,400 miles above the Earth's surface. These satellites give meteorologists the ability to constantly track weather systems that impact the region below them.

Evaporation - The process by which water changes phase from a liquid to a vapor. Energy from the sun and wind are the main drivers of evaporation. 80% of evaporation occurs over the oceans, while the remaining 20% occurs over land. The highest evaporation rates occur when the relative humidity is low on a hot and windy day.

Tropic of Capricorn - The Tropic of Capricorn is an imaginary line of latitude going around the Earth at approximately 23.5 degrees south of the equator. It is the southernmost point on Earth where the sun's rays can be directly overhead. On the day of the Northern Hemisphere's winter solstice, the sun will be directly overhead at noon here.