Dust Bowl - An extended period of exceptional drought that affected the Great Plains of North America during the 1930s. Agricultural activities were crippled during this epic drought. Heat waves and occasional dust storms were fairly common during the dust bowl years. On some occasions, the dust storms in the Plains made it all the way to the east coast.

isodrosotherm - A line of equal dew point temperature. Isodrosotherms are typically drawn for surface dew points. They can give meteorologists a good read on where surface fronts are located since tightly packed isodrosotherms indicate a dew point gradient.

Colorado Low - A low pressure system that forms in eastern Colorado or northeastern New Mexico. These types of lows typically track northeastward across the central Plains of the U.S. over a period of several days. Some of the strongest blizzards that occur during the winter season are oftentimes the result of a Colorado low.

Equinox - Time of year when day and night are nearly equal in length. The equinoxes signal a transitional time of year. In the northern hemisphere, the autumnal equinox is the transition season that leads up to winter. Conversely, the vernal equinox is the transition season of spring that leads to summer. On the equator, the sun can be seen directly overhead at noon on the day of an equinox.

Squall Line - A line of intense thunderstorms that are accompanied by high winds and heavy rain. Squall lines typically move through quickly and oftentimes occur along or ahead of a fast moving cold front. These lines can sometimes extend for hundreds of miles.

Radar Echo - What meteorologists refer to when diagnosing radio waves that are reflected back to the radar antenna. This occurs when the radio waves emitted by the radar run into precipitation as well as non-weather related phenomenon such as insects. The radar translates the returned signal into a visual display showing the radar echoes position from the radar site.

Civil Twilight - Is defined to begin in the morning, and to end in the evening when the center of the Sun is geometrically 6 degrees below the horizon. This is the limit at which twilight illumination is sufficient, under good weather conditions, for terrestrial objects to be clearly distinguished. During civil twilight artificial lighting is no longer required as long as clear skis are present. Only the brightest stars and planets can be seen by the naked eye during civil twilight.