thunderstorms

• Cumulus Stage- This vertical moving, unstable air mass forms a cumulus, or towering cumulus, cloud as it begins to condense and releases energy. The release of heat allows the area to become warmer causing the air to rise more. This rising air creates an updraft of air. The water droplets begin to coalesce which eventually overcome the updraft and fall as precipitation. This is stage one of the formation of a thunderstorm. There is very little rain and occasional lightning with the developing towering cumulus stage
• Mature Stage of a thunderstorm

  1. Cloud becomes a cumulonimbus cloud

  2. Cloud rises between 5–10 miles high (8–16 km)

  3. Rising stops when temperature of cooling air is same as air around it

  4. Updrafts can be as strong as 40 mph (59 km/hr)

  5. Precipitation begins to fall and cools the air

  6. Evaporation from precipitation allows air to cool

  7. Cold air sinks creating downdrafts

  8. Cumulonimbus cloud has equal amount of air rising and sinking

  9. Top may fan out in an anvil top

  10. Lightning, heavy rain, hail, strong winds, and tornadoes can occur

  11. Thunderstorms may form, grow, and dissipate in as little as 30 minutes
• Dissipation Stage- As the rain continues to cool the surrounding air by evaporation, the downdrafts get stronger. In order for the thunderstorm to remain strong, it would need large amounts of warm, moist rising air to feed it. Once there is more air cooling and sinking, the thunderstorm will begin to dissipate. A secondary effect happens when the cool downdrafts fan out over the Earth's surface, further cooling it. Once the Earth's surface is cool and no longer providing the warm, rising air, the thunderstorm will dissipate.
• Thunderstorms

  Form from moist, unstable air being lifted vertically due to the heating of the Earth's surface
• Between 1,800 and 2,000 thunderstorms have formed somewhere on the planet while you are reading this
• There are about 44,000 thunderstorms every day
• Stages of Development of a Thunderstorm

  1. Cumulus Stage

  2. Mature Stage

  3. Dissipation Stage
• Cumulus Stage


  • Vertical moving, unstable air mass forms a cumulus cloud as it begins to condense and releases energy
  • Rising air creates an updraft
  • Water droplets begin to coalesce and overcome the updraft, falling as precipitation
• Mature Stage


  • Cloud has become a cumulonimbus cloud and risen 5-10 miles high
  • Updrafts can be as strong as 40 mph
  • Precipitation begins to fall, cooling the air and creating downdrafts
  • Lightning, heavy rain, hail, strong winds, and tornadoes can occur
• Dissipation Stage


  • Downdrafts get stronger as rain cools the surrounding air by evaporation
  • Thunderstorm will dissipate once the Earth's surface is cool and no longer providing warm, rising air
• Severe Thunderstorms


  Have at least one of the following: tornados, hail larger than three-quarters of an inch, or winds greater than 58 mph
• Severe Thunderstorms


  • Updraft is so strong it creates an overshooting top, indicating fast-rising warm air
  • Supercells can have updrafts of 70 mph that can carry hail
  • Tilted, rotating supercells can maintain upward flow of warm air
• Downburst


  A cold mass of air falling rapidly through the supercell towards the ground and bursting out, causing damage similar to a tornado
• Macroburst


  A burst of air exceeding 2.5 miles in diameter with winds up to 124 mph
• Microburst


  A burst of air less than 2.5 miles in diameter with winds up to 155 mph
• Lightning Formation


  1. Friction of updrafts and downdrafts produces static electricity

  2. Positively charged ions head towards top of cloud, negatively charged ions head towards ground

  3. Negatively charged ions (step leader) and positively charged ions (streamer) meet, forming a lightning channel
• The temperature inside and around the lightning flash is somewhere between 28,000°C and 30,000°C
• Lightning travels at the speed of light, but sound travels much slower, so you hear the thunder later