El Nino - An anomalous warming of ocean waters in the east central equatorial Pacific. El Nino events occur every two to seven years and have local as well as global impacts. Nutrient deficient waters cripple the fishing industry off the coast of western South America during El Ninos, while global weather patterns can be significantly altered due to the presence of an El Nino.

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.

Millibar - A millibar is a measure of atmospheric pressure taken by a barometer. The standard pressure measured at the surface is 1,013 millibars. Other units that are used for pressure measurements are inches of mercury and pascals. The lowest pressure readings that have occurred at the surface have been measured underneath intense hurricanes.

In Situ - In Situ is taken from Latin and means in one place. In meteorology, it refers to atmospheric measurements taken at the location of the entity being measured. The other way of measuring atmospheric entities is done using remote sensing. Remote sensing is when atmospheric measurements are taken by remote sensors that are far away from the locations they are taking readings. Weather Satellites are examples of remote sensors.

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.

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.

Forecast - A prediction of coming events or conditions. Forecasts are commonly used in business and weather.