Transcript PowerPoint Weather Slideshow

What’s Up With That Weather?
Why Does It Rain?
• When rain clouds are pushed up into cold air
the rain drops form and become heavy
enough to be pulled to the ground by gravity.
• Water from the sea, rivers, lakes, ponds,
pools and puddles is heated by the sun and
evaporated into water vapor.
• Clouds are made up of millions of tiny water
vapor droplets, which cling together.
What’s Snow?
 Snow falls from clouds that contain enough cloud droplets and ice
crystals for precipitation to form.
 In order for snow to reach the ground without melting, the wet bulb
temperature of the air near the ground must be below freezing.
 The wet bulb temperature is the temperature measured by a
thermometer that has a little wet sock covering the bulb before it is
swung in a circle in the air.
 Thus, you can have snow fall reaching the ground even when the air
temperature is slightly above freezing.
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Hurricanes are severe tropical storms that form in the southern Atlantic
Ocean, Caribbean Sea, Gulf of Mexico, and in the eastern Pacific
Ocean.
Hurricanes gather heat and energy through contact with warm ocean
waters. Evaporation from the seawater increases their power.
Hurricanes rotate in a counter-clockwise direction around an "eye."
Hurricanes have winds at least 74 miles per hour.
When they come onto land, the heavy rain, strong winds and heavy
waves can damage buildings, trees and cars.
The heavy waves are called a storm surge.
Storm surges are very dangerous and a major reason why you MUST
stay away from the ocean during a hurricane warning or hurricane.
• The action of rising and descending air within
a thunderstorm separates positive and
negative charges.
• Water and ice particles also affect the
distribution of electrical charge.
• Lightning results from the buildup and
discharge of electrical energy between
positively and negatively charged areas.
• Most lightning occurs within the cloud or
between the cloud and ground.
The Blowing
Wind is moving air.
The sun makes the wind blow.
The energy in wind comes from the
sun.
When the sun shines it heats the
earth.
The air over the land gets hotter
then the air over the water.
The hot air raises and cooler air
rushes in to take its place.
The moving air is wind.
El Niño
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In the tropical Pacific, trade winds
generally drive the surface waters
westward.
The surface water becomes warmer
going westward because of its
longer exposure to solar heating.
El Niño is observed when the
easterly trade winds weaken,
allowing warmer waters of the
western Pacific to migrate eastward
and eventually reach the South
American Coast.
The cool nutrient-rich sea water
normally found along the coast of
Peru is replaced by warmer water
depleted of nutrients, resulting in a
dramatic reduction in marine fish
and plant life.
References
Suggested Reading
• Why Does Lightning Strike?
• Elmer's Weather
• Sandra's Sun Hat
Suggested Websites
• The Water Cycle
• Rain
• The Weather Channel