Thunderstorm - A local storm that spawns from a cumulonimbus cloud and is accompanied by lightning and thunder. The atmospheric conditions needed to produce a thunderstorm are warm and moist conditions in the low levels. It is estimated that around 1,800 thunderstorms are occurring on Earth at any given moment.

Lilapsophobia - This is the fear of tornadoes/hurricanes. People that have lived through the occurrence of a severe hurricane or tornado are most susceptible to this phobia.

Air Mass Thunderstorm - Generally, a thunderstorm not associated with a front or other type of synoptic-scale forcing mechanism. Air mass thunderstorms typically are associated with warm, humid air in the summer months; they develop during the afternoon in response to solar heating, and typically have a short lifespan. They are less likely to be severe than other types of thunderstorms, but they are still capable of producing gusty winds, brief heavy rain, and (in extreme cases) hail over 3/4 inch in diameter.

sounding - A sounding is the graphical output taken by a rawindsonde which is launched with a weather balloon to record various atmospheric variables in differing altitudes. Temperature, moisture, and wind speed/direction are most commonly measured when a sounding is taken. The data can be plotted on a diagram called a skew-t diagram which can give important details on the atmosphere such as how stable or unstable it is.

Nacreous Clouds - Nacreous clouds are rare and are rarely found too far south of the poles. They form at an impressive elevation between 68,000 to 100,000 ft where temperatures are at or below -108F. They appear as large thin discs which tend to reflect vivid colors. Due to their high elevations, they can only be seen when the sun is just below the horizon.

Brontophobia - This phobia is defined as the irrational fear of thunder. For those who suffer, it creates high anxiety even though the thunder may pose no real threat to them.

Nautical Twilight - Is defined to begin in the morning, and to end in the evening, when the center of the sun is geometrically 12 degrees below the horizon. At the beginning or end of nautical twilight, under good atmospheric conditions and in the absence of other illumination, general outlines of ground objects may be distinguishable, but detailed outdoor activities are not possible. During nautical twilight the illumination level is such that the horizon is still visible, even on a Moonless night, thereby allowing mariners the ability to take reliable star sights for navigational purposes.