Nautical Twilight - Is defined to begin in the morning, and to end in the evening, when the center of the sun is geometrically 12 degrees below the horizon. At the beginning or end of nautical twilight, under good atmospheric conditions and in the absence of other illumination, general outlines of ground objects may be distinguishable, but detailed outdoor activities are not possible. During nautical twilight the illumination level is such that the horizon is still visible, even on a Moonless night, thereby allowing mariners the ability to take reliable star sights for navigational purposes.

Cryosphere - This term refers collectively to the portions of the Earth where water is in solid form. This includes areas with snow cover, floating ice, glaciers, ice caps, ice sheets, along with areas of frozen ground. The area of the cryosphere shrinks during the summer season and then grows during the winter.

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.

Tropic of Cancer - The Tropic of Cancer is a line of latitude circling the Earth at approximately 23.5 degrees north of the equator. It is the northernmost point on Earth where the sun's rays can appear directly overhead. This occurs each year at noon on the day of the summer solstice.

Ground clutter - Radar returns that are received from stationary ground-based targets. Most ground clutter is located 30 miles or less from the radar site, unless a temperature inversion is present. When a temperature inversion is present, the radar beam bends downward towards the earth's surface, creating ground clutter much farther away from the radar site. Common sources of ground clutter are hills, buildings, wind mills, and even wave crests at sea.

Cirrostratus clouds - A widespread, thin high level cloud that is composed of ice crystals. These clouds form a thin veil-like layer over the entire sky. When sunlight or moonlight passes through these clouds, a ring or halo may form. Many times cirrostratus clouds arrive 12-24 hours before a rain or snow event.

Lenticular clouds - The scientific name is altocumulus standing lenticular clouds. These lens shaped clouds are the most common cloud type to be mistaken for UFO's. They are most common near mountain ranges, as they form when strong winds blow up and over the top of a mountain range. Even though the winds within these clouds are moving very quickly, the cloud formation itself remains stationary. The presence of a lenticular cloud signifies an area of severe turbulence in the atmosphere, as pilots avoid them when possible.