Precipitation & Storms

Target #24- I can identify the different types of precipitation

• Any moisture that falls from the air to earth’s surface is called precipitation– Liquid form• Rain

– Small drops are referred to as drizzle– Northeastern colloquialism= “It’s spitting outside”– If the temperature of the rain is below 32o F, but it

is still liquid, it is called freezing rain

– Frozen forms• Snow• Sleet• Hail

Target #25- I can summarize the two causes of precipitation can form

• Causes of precipitation– Coalescence• The formation of large

droplets of precipitation by the combining of smaller droplets• As the droplets fall from

clouds, they collide and combine with other droplets

– Supercooling• A condition in which a

substance is cooled to below its freezing point, condensation point, or sublimation point without changing state

Target #26- I can state what tools scientists use to measure precipitation

• Meteorologists use a variety of instruments to measure precipitation– Rain gauge- measures

the amount of liquid precipitation that falls

–Measuring stick- measures the amount of snowfall

Target #27- I can list the types of severe weather

• Severe weather is weather that may cause property damage or loss of life– Can include:• Large quantities of rain• Lightning• Hail• Strong winds• tornadoes

Target #28- I can describe how a heavy storm develops

• A heavy storm that is accompanied by rain, thunder, lightning, and strong winds is known as a thunderstorm– Develop in three stages

• Cumulus stage: warm, moist air rises, the water vapor condenses to form a cumulus cloud

• Mature stage: condensation continues as the cloud rises and becomes a dark cumulonimbus cloud– Torrential rain or hail may fall– Severe winds usually occur

• Dissipating stage: strong downdrafts stop the air currents from rising– The decrease of available water vapor

causes the storm to die

Target #29- I can state how lightning & thunder forms

• During thunderstorms, lightning can form– Lightning occurs

when clouds discharge electricity• Visible as a strike of

light

– The released electricity heats the air, and the air expands rapidly producing thunder

Target #30- I can explain how Doppler radar is used to study weather patterns

–Doppler Radar• Measures the intensity of

precipitation–Can also measure wind

speed, direction, and intensity

• Commonly used for communicating weather forecasts• Works by bouncing radio

waves off rain or snow–By timing how long the wave

takes to return, meteorologists can detect the location, direction of movement, and intensity of the precipitation

Target #31- I can state how scientists use satellite images to study weather activity

• Scientists can also study satellite images of weather activity– By determining the location of storms,

scientist can calculate the speed of wind, the rate at which storms moving, and the direction weather is travelling

– Scientist can also learn more about how storms form and the factors that influence their movement.