Mesopause - This is the portion of the Earth's atmosphere that divides the mesosphere from the thermosphere. The mesopause is where the temperature of the atmosphere reaches its minimum. The coldest temperatures on Earth are found here as temperatures can fall to as low as -148F.

Derecho - A widespread and usually fast-moving complex of thunderstorms that produce damaging straight-line winds. These systems are long lived, as the swath of wind damage associated with them extends for hundreds of miles. Wind gusts can range from 60 to over 100 mph in a derecho.

Dew - Water that has condensed onto objects near the ground when the surface temperature of the object falls below the dew point. The most common surfaces that dew will form on are grasses and other vegetation. Dew can be an important source of moisture for plants during a drought.

Synoptic Scale - In meteorology this refers to the study of large scale systems that develop in the atmosphere. Major cyclones and their associated fronts are a commonly studied feature in synoptic meteorology. In order to be on the synoptic scale, a system must stretch across a distance of at least 600 miles.

Anvil - The flat, spreading top of a cumulonimbus cloud, often shaped like an anvil. Anvils are a result of strong winds near the top of the thunderstorm. Thunderstorm anvils may spread hundreds of miles downwind from the thunderstorm itself, and sometimes may spread upwind.

Keraunophobia - Keraunophobia is the irrational fear of thunder and lightning.

Tornado - A violently rotating column of air that reaches the ground from the bottom of a severe thunderstorm. Tornadoes become visible due to clouds associated with them as well as the dust and debris that get sucked into them. The US sees more tornadoes than any country in the world as around 1,200 can be expected each year.