Nephophobia - The irrational fear of clouds. This is derived from the Greek word for clouds, which is nephos.

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'.

Zodiacal Light - A softly luminous cone of white light visible from an hour or so after sunset or before dawn. The cause of this pre-dawn or post-dusk light is created by sunlight that reflects off of grains of dust in space between the Earth and the Sun. To an unknowing observer it can be mistaken for a glare of city lights on the distant horizon.

Tropic of Capricorn - The Tropic of Capricorn is an imaginary line of latitude going around the Earth at approximately 23.5 degrees south of the equator. It is the southernmost point on Earth where the sun's rays can be directly overhead. On the day of the Northern Hemisphere's winter solstice, the sun will be directly overhead at noon here.

Permafrost - A layer of subsoil that remains at a temperature of 32 degrees or colder throughout the entire year. Areas that have permafrost are mainly confined to high latitudes near the poles as well as high mountain ranges. The warming climate that is being experienced on Earth is decreasing the areal coverage of permafrost.

Exosphere - The Exosphere is the outermost layer of the atmosphere. It extends from the top of the thermosphere and is 6,200 miles thick. In this layer, atoms and molecules escape into space and satellites orbit the earth. Some scientists place the outer reaches of the exosphere about 120,000 miles from the earths surface, making it near the half way point to the moon.

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.