Extreme+Weather

Extreme Weather: Thunderstorms

Thunderstorms: Thunderstorms form when wet, unstable air is lifted vertically into the atmosphere. This is caused by... 1. Unequal warming of the Earth's surface 2. Lifting due to topographic obstruction of the air flow (such as mountains) 3. Dynamic lifting due to the presence of the frontal zone 4. High dew point

**Types of Thunderstorms:** ~ Typically last 20-30 minutes ~ Pulse storms produce severe weather elements, such as downbursts, hail, heavy rain, and/or weak tornadoes
 * - Single-Cell Storms ** (air mass storms)

**- Multicell Cluster Storms** ~ These are groups of cells moving as a single unit, with each cell in a different stage of the thunderstorm life cycle ~ Can produce moderate size hail, flash floods, and/or weak tornadoes ~ Thunderstorm with a rotating updraft ~ Can produce strong downbursts, large hail, occasional flash floods, and/or weak to violent tornadoes ~ A line of storms with continuous, well-developed gust front at the leading edge of the line ~ Produce moderate-sized hail, occasional flash floods, and/or weak tornadoes
 * - Supercells ** (mesocyclones)
 * - Multicell Line Storms** (squall lines)

**Occurrences During Thunderstorms:** **- Hail** ~ Precipitation in the form of small ball or lumps usually consisting of concentric layers of clear ice ~ Hail forms when small droplets of water freeze in the towering cumulonimbus cloud, and are tossed up and down by strong winds within the cloud. Each time it nears the surface, it gets wet, and when it is tossed back upward, the layer freezes. Thus, the larger the hailstones, the strongers the winds of the storm. ~ Lightning occurs because friction between cloud droplets builds up negative charge in the cloud, which is attracted to the positive charge in the ground ~ Air in a lightning strike can get up to 54,000 degrees Fahrenheit, which is 6 times hotter than he surface of the Sun ~ Thunder occurs because the heat from a lightning strike expands the air, actually exploding it so that it creates the signature rumble of thunder ~ To determine the distance of a storm by the sound of thunder, count 5 seconds for every mile immediately after a lightning strike. When thunder rumbles, that's how far away the storm is. (So if you count to 15 after a lightning strike before you hear thunder, the storm is about 3 miles away) ~ Downbursts are produced by cold column of air shooting straight down from a cumulonimbus cloud, that, when it reaches the ground, spreads out in all directions. This creates many strong gusts of wind.
 * - Lightning & Thunder **
 * - Downbursts **