How Do Storms Form?

Clouds 3 main types – Cumulus – Cirrus – Stratus – cumulonimbus

How do clouds form? Warm air rises and then cools Water vapor is added to the air Eventually, air becomes saturated (100% humidity) Water vapor condenses on smoke, dust, salt and other small particles suspended in the air Millions of tiny drops of water collect and form a cloud

Make Mrs. Biggers Proud! Greek and Latin roots: – Nimbus or nimbo: more likely to produce precipitation – Cirro- high altitude – Alto- middle altitude – Strato- low altitude

Can you use an airplane trail to predict the weather?? What appears to be a white trail of smoke from an airplane’s engine is not smoke- it’s condensation The engine and combustion of fuel creates heat Heat + cold temps at high altitudes = condensation A thick “contrail” that doesn’t dissipate is a sign that a frontal system is approaching!

Precipitation Water or ice that falls from the air to Earth – Rain – Sleet: forms when rain falls through a layer of freezing air – Snow: formed when water vapor freezes – Hail: balls or lumps of ice that form in cumulonimbus clouds Caused by updrafts of air pushing rain back into the freezing air

Did you know… Meteorologists can artificially cause precipitation? Cloud seedling

Hmmmmm… Why do you think some clouds are formed from water droplets, but others are made up of ice crystals? How can rain and hail fall from the same cumulonimbus cloud?

Thunderstorms Generally occur along cold fronts, forming a cumulonimbus cloud 2 atmospheric conditions required: – Warm/moist air near Earth’s surface – Unstable atmosphere occurs when the surrounding air is colder than the rising air mass Air mass will continue to rise as long as the surrounding air is colder

Thunderstorms Are very powerful! One typical thunderstorm generates enough electrical energy to provide power to the U.S. for 20 minutes.

Lightning Electric discharge between positively charged area and a negatively charged area When lightning strikes, energy is released and causes the air around it to expand rapidly Expansion of air sends out sound waves, which you hear as thunder

True or False? Lightning never strikes in the same place twice.

Colorful Lightning Can indicate atmospheric conditions: Blue indicates hail Red indicates rain Yellow or orange indicates dust White indicates low humidity

Severe Thunderstorms Severe thunderstorms can create: – High winds – Hail – Flash floods – tornadoes

Twists of Terror Tornadoes only occur during about 1% of all thunderstorms Has high wind speeds and low central air pressure Starts as a funnel cloud

How a Tornado Forms Wind moves in two different directions- the air in the middle starts to spin Strong updrafts of air turn the spinning air to a vertical position in a cumulonimbus cloud Spinning column of air forms a funnel cloud Funnel cloud touches the earth and becomes a tornado

Tornado Facts 75% of the earth’s tornadoes occur in the U.S. Spring and early summer is tornado season Cold, dry air from Canada meets warm, moist air from the tropics- prime tornado conditions

Hurricane Large, rotating tropical storm Winds speeds of at least 120 km/h Also called typhoons and cyclones

Naked Chicken?

How Do Hurricanes Form? Begins as a group of thunderstorms moving over tropical ocean waters Winds traveling in two different directs meet Coriolis effect causes hurricanes to turn in different directions in South and North Hemispheres

Most Powerful Storms on Earth Hurricanes get their energy from the condensation of water vapor SAY WHAT?

Tropical storms form over warm ocean waters The warmer the water, the more water vapor is in the air Storm winds carry the water vapor into the air As water vapor and warm air rise, the water vapor condenses and releases large amounts of energy

Cross-Section of a Hurricane Eye of the storm Eye wall Rain Bands