Scintillation - The apparent twinkling of a star due to its light passing through regions of differing air densities in the atmosphere. This results in the light being refracted and scattered before it reaches the viewer.

Advection Fog - Advection fog often looks like radiation fog and is also the result of condensation. However, the condensation in this case is caused not by a reduction in surface temperature, but rather by the horizontal movement of warm moist air over a cold surface. This is very common during the winter when warm moist winds blow over cold snowcover. Advection fog may also form when moist maritime air masses drift over a cold inland area. This usually happens at night when the temperature of the land drops due to radiational cooling.

Pluie - This is the french word for rain. To say, "it is raining today" one would say, "Il pleut aujourd'hui."

Verglas - Taken from the French language, this is a term that is used to describe a thin coating of ice that forms on an object, such as a rock.

Advection Fog - Advection fog often looks like radiation fog and is also the result of condensation. However, the condensation in this case is caused not by a reduction in surface temperature, but rather by the horizontal movement of warm moist air over a cold surface. This is very common during the winter when warm moist winds blow over cold snowcover. Advection fog may also form when moist maritime air masses drift over a cold inland area. This usually happens at night when the temperature of the land drops due to radiational cooling.

Arctic Oscillation - A climate phase that looks at the strength of the winds surrounding the arctic region. During a positive phase of the arctic oscillation, the ring of winds around the arctic remain strong, thereby holding the coldest air masses near the pole. During the negative phase these upper level winds weaken, allowing for the bitter cold arctic air masses to head further south across the northern hemisphere. Each switch in phase can last weeks or even months.

Contrail - A contrail is the condensation trail that is left behind by a passing jet plane or rocket. Contrails form when hot humid air from jet exhaust mixes with ambient air that is colder and drier. Contrails are composed of water droplets, and can therefore be thought of as a man-made cloud streak.