Civil Dawn - The time of morning at which the sun is 6 degrees below the horizon. At this time, there is enough light for objects to be distinguishable and for outdoor activities to commence.

Indian Summer - A period of unseasonably warm and sunny weather that occurs from late September to mid November. In parts of the country, the first killing frost of the season must occur before a late autumn warm spell can be coined 'Indian Summer'.

Ice Fog - This type of fog forms when the air temperature is well below freezing and it's composed entirely of tiny ice crystals that are suspended in the air. Ice fog will only be witnessed while in the midst of an arctic air mass. Generally, the temperature needs to be 14F or colder in order for ice fog to form.

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.

Jet Stream - Intense winds that are concentrated in a relatively narrow stream in the upper atmosphere. Most jet streams are found at around 30,000 ft up in the atmosphere. The two jet streams that impact the US are the polar and subtropical. Both act as highways for weather systems to travel along.

Gravity Waves - These waves occur between any stable layers of fluids of different density. When the fluid boundary is disturbed, buoyancy forces try to restore the equilibrium. The fluid returns to its original shape, overshoots and oscillations then set in, which propagate as waves. Gravity or buoyancy is the restoring force. A crude example of what gravity waves look like can be seen when you throw a rock in a calm pond. The ripples that spread out across the pond can be compared to propagating gravity waves.

Cloudburst - A sudden, heavy rain shower that tends to be localized and of a brief duration. Most cloudbursts occur within thunderstorms.