Bell Ringer Two types of isopleths are isobars and isotherms. Isobars show areas of equal __________ and isotherms show areas of equal ______________. air pressure temperature

Thunderstorms

Thunderstorm Factors At any given moment, nearly 2000 thunderstorms are occurring around the world Thunderstorms form from cumulonimbus clouds (anvil-shaped clouds) Can be very severe, but usually last only about 30 minutes

Anvil?

Thunderstorm Factors Thunderstorms need: Warm, humid air Unstable atmosphere (allows a convection current to occur)

Thunderstorm Factors Latent Heat -- heat energy stored in water vapor that is released during condensation When air rises, it begins to cool down. The water vapor condenses into liquid water and releases the latent heat energy into the air.

Thunderstorm Factors This heat warms up the cloud and causes it to lift up higher (because warm air rises), which causes more and more water vapor to condense… and release heat…

Thunderstorm Formation Three stages to thunderstorm formation Cumulus Stage – cumulus cloud forms, latent heat is released, cloud droplets join together (coalesce) and fall as precipitation

Thunderstorm Formation Mature Stage – precipitation cools the air, creates a convection current of updrafts (warm air rises) and downdrafts (cool air sinks) Dissipation Stage – air cools, convection slows and then stops (and the storm dies out)

Dangers of Thunderstorms Only about 10% of thunderstorms are considered severe, and even fewer are considered supercells Supercells – self-sustaining, extremely powerful storms with intense rotating updrafts

Supercell Timelapse https://www.youtube.com/watch?v=VoO89cqDgJU

Dangers of Thunderstorms Lightning – a discharge of electrons (electricity) from a thundercloud to the ground, cloud to cloud, or ground to cloud

Dangers of Thunderstorms The negatively-charged air in the cloud moves towards the positively-charged ground, which creates lightning

Dangers of Thunderstorms Lightning heats the air to around 30,000oC, which is 5 times hotter than the surface of the Sun! At this temperature, air expands explosively and creates the sound of thunder (thunder is the effect of lightning) Because sound travels more slowly than light, you typically see lightning before you hear thunder

Dangers of Thunderstorms

Dangers of Thunderstorms Each year, lightning causes about 7500 forest fires, 300 injuries, and 93 deaths

Lightning Strike Cary, NC http://www.wral.com/man-28-killed-after-lightning-strike-in-cary-crossroads/14571960/

Dangers of Thunderstorms Hail – precipitation in the form of lumps of ice Rain droplets get caught in the updrafts and downdrafts, creating a cycle of adding moisture and refreezing until it gets too heavy and falls out of the cloud as hail

Dangers of Thunderstorms Floods – occur when a thunderstorm moves slowly over one location, dumping all its rain in one place Main cause of thunderstorm-related deaths in the US

Spend the next few minutes studying for your quiz. Write clearly, put answers in blanks, and attempt all questions! Hand in to the front basket when done and get vocab. Vocabulary needs to be completed in class. VOCAB QUIZ ON ASSIGNMENTS 1&2 TUESDAY!

You Be the Teacher Your group will become experts in either a type of severe weather or about climate. You will research this topic and on review day present this information to the class. EVERYONE MUST PARTICIPATE. Part of your grade will be based on participation.

You Be the Teacher You supply the notebook paper. Computer paper (for your drawing) is at Stn 2. Markers (1 box/group only) and rulers are at Stn 1. EACH PERSON needs a textbook. Return textbooks to a BOOKSHELF at the end of class.