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Hurricanes Unit Study & Lapbook

Our Atmosphere on Planet Earth

Atmosphere
Explain to your student that the atmosphere is like a blanket of air that covers all of  the Earth and makes it possible for life (people, plants, and animals) to survive on this planet.  It is hundreds of miles thick and composed of gases including oxygen (what humans need to breathe), carbon dioxide (what plans need to grow and make food), and nitrogen.

The atmosphere also serves as a shield that blocks some of the sun's rays during the day so that the Earth doesn't get too hot.  It also helps hold the sun's heat; this keeps the Earth from getting too cold at night. 

Terms to Know

Weather- changes in the part of the atmosphere that's closest to Earth's surface

Troposphere- the bottom 10 miles of the atmosphere; this is where all the weather happens

Meteorologists- scientists who study the weather; to become one, you have to know a lot about science, math, and computers

Meteorologists use lots of tools to gather information about the weather in order to make predictions about the future weather. Here are some tools that meteorologists use--

1. anemometer- measures wind speed
2. wind vane- shows direction of wind
3. rain gauge- measures rainfall
4. barometer- measures air pressure
5. hygrometer- measures humidity
6. thermometer- measures temperature of the air

Wind

Wind- is caused by an uneven heating of the atmosphere.

How Wind Forms
1. The sun doesn't warm the Earth evenly; some places get much hotter than others.  The sun actually warms the ground not the air.  Then the ground warms the air.
2. Warm air is lighter than cold air, so when an area on the surface is warmed by the sun, the air above that are rises up to the sky.
3. When warm air rises, air from somewhere else moves in to takes its place.  This moving air is known as wind.
4.  The weather changes because of the cool and warm air moving all around.

Beaufort Scale
One of the first scales to estimate wind speeds and effects was created in 1805 by Admiral Sir Francis Beaufort from Britain.  It was designed to help sailors estimate winds.  It is still used today for the same purpose.    It is based on a scale from 0 to 12 (with 12 being the roughest wind).

0 Calm (not included in minit book)
1 Light Air- 1-3 mph; smoke drifts and wind vanes stay still
2 Slight Breeze- 4-7 mph; leaves rustle and wind vanes move
3 Gentle Breeze- 8-12 mph; leaves and twigs move constantly; flags are unfurled and flapping
4 Moderate Breeze- 13-18 mph; dust and loose paper blow around; branches move in the trees
5 Fresh Breeze- 19-24 mph; small trees sway in the wind
6 Strong Breeze- 25-31 mph; large branches sway; air whistles around phone and power lines
7 Moderate Gale- 32-38 mph; whole trees sway in the wind; it gets a little hard to walk
8 Fresh Gale- 39-46 mph; twigs break off trees
9 Strong Gale- 47-54 mph; branches break off trees; shingles blow off of rooftops
10 Storm- 55-63 mph; trees are broken or pulled out of the ground; buildings are damaged
11 Whole Gail (Violent Storm) - 64-73 mph; trees blow across the ground; most buildings get some damage
12 Hurricane- 74 mph+; extreme destruction; trees and power lines are knocked down

High Pressure Areas & Low Pressure Areas
High-pressure Area- cold air is heavier than warm air so it PRESSES down harder on Earth's surface; high-pressure areas are areas of cold air
Low-pressure Area- warm air is lighter than cold air and doesn't press down as hard on the Earth's surface.
Air always moves from high-pressure areas to low-pressure areas.

The Equator is the area around the middle of the earth.  Weather there is warm-- warmer than it is at either pole.  This is because the Earth is tilted as it moves around the sun causing the sun to shine down at an angle on the poles while shining straight down on the equator. 

Clouds

How Clouds Form

1. Warm air, full of water vapo (invisible water that is always in the air)r, rises
2. Rising air cools off
3. Water vapor condenses into water droplets and ice crystals
4. These water droplets and ice crystals form clouds

Types of Clouds

Cirrus Clouds-
Seven miles above Earth.  These are feathery white clouds made by the wind blowing ice crystals.  You usually see these clouds in the sky on a fair weather day. 

Stratus Clouds-
These clouds are located 1mile above the Earth.  They are hang like flat grey sheets in the sky and often cover the entire sky.  When they do cover the sky, the weather forecast is overcast.   Fog occurs when stratus clouds touch the ground.

Cumulus Clouds-
Cumulus clouds are found 3 miles above the Earth.  They look like puffs of cotton and are made mostly of water droplets.  They usually form during fair weather and they are constantly changing shape.

Cumulonimbus Clouds-
These are 2-3 miles above Earth.  They start as cumulus clouds; they grow tall and are dangerous!  They can be over 12 miles high and are caused by strong winds.  They are composed of swirling air, water, and ice and give birth to thunderstorms and tornadoes.

Why are storm clouds dark?  They are dark because they are tall and thick; they are so thick that they block out light from the sun.

Rain

How Rain Forms
Remind your student that clouds are formed from water droplets and ice crystals.  When these start colliding, some of them stick together and form larger drops.  Larger drops mean heavier drops.  If they get too heavy for the cloud to hold them, they fall to the ground.

Make Your Own Rain Cloud
1.  Fill a large plastic bottle with hot water
2.  Pour out 2/3 of the water
3.  Place an ice cube on top of the bottle
4.  The hot water gas forms a misty cloud when it meets the cold ice cube air

How Does a Storm End?
Most storms last 20 minutes to an hour.  The next time you have a storm, time it with your student to see how long it lasts.
Throughout the storm, warm air is constantly feeding it with moisture.  It begins to calm down when the precipitation (rain, hail, etc.) chill the ground putting an end to updrafts to feed the clouds.   Once all the water (moisture) in the clouds has fallen, the storm is usually over. 

Lighting and Thunder

Lighting
The air inside a storm cloud is very busy-- wind is swirling, water droplets and ice crystals are being blown everywhere.  This action can create electricity which is strong enough to make a spark.  This spark is known as lightning which can be five times as hot as the surface of the sun!  Yikes!

Lightning is great at jumping!
1. It can jump from place to place in a cloud
2. It can jump from cloud to cloud
3. It can jump from cloud to ground

Thunder
The amount of heat put out by lightning causes the air around the bolt to spread out very quickly.  This makes a booming sound.  The sound can tell you how far away lightning is.   Count the seconds between the lightning and the thunder.  Divide by five-- it takes five seconds for sound to travel one minute.    You see lightning before you hear thunder because light travels faster than sound.

Hail

Ice chunks form when wind caries a water droplet up inside a tall, cold cloud where it stays until the droplet freezes.  As the droplet falls back down through the cloud, it collects a layer of moisture on the outside.  Next, it's caught in another updraft and freezes again making the hailstone bigger.  The hailstone travels up and down inside the cloud multiple times until it gets too heavy to be carried up again.  You can cut open a hailstone and count the rings to discover how many times it has gone up and down in a cloud.

Hurricanes

The word hurricane is from the Spanish word huracan meaning a big wind.  Hurricanes are known by other names, too (see below).   Hurricanes are the most dangerous storms on earth.  Even though the winds are only about half as fast as a tornado, a hurricane can be 2,000 times as wide as a tornado!  Most hurricanes last less than an hour, but others go on and on for days! 

Hurricanes are Also Known As...
Hurricanes- Caribbean Sea, Southern U.S., Central America
Typhoons- China Sea, northern Panic Ocean including the Philippines, Japan and southern China
Cyclones- Indian Ocean including northern Australia, Indonesia, India, and Bangladesh

How Does a Hurricane Form?
1. Get out your globe and show your student the tropics (Tropic of Capricorn, Tropic of Cancer).  The climate in the tropics is very warm-- the warmest on Earth-- which means the air can hold a lot of water vapor.  Cold fronts sneaking in to the tropics or low pressure in the tropics causes a tropical disturbance.    Conditions for a tropical disturbance to turn into a tropical storm -
    ~thunderstorms are present
    ~the disturbance is 300 miles from the equator
    ~ocean temperatures are 80 degrees F or more (to a depth of 164 feet below the surface); this is one of the most important conditions for the        
      formation of a hurricane
    ~lots of moisture in the lower and middle part of the atmosphere
    ~not too much change in wind speed; winds need to come from the same direction

2.  Several storms can crop up together and become one system known as a tropical depression.  The storms will join and spin together.  It is called a depression because it has low (depressed) air in the center which causes winds.  The lower the pressure goes, the stronger the winds are.   Depressions don't typically have eyes or cyclonic shapes.  If the winds of the storm reach 39 mph, it is considered a tropical storm.

3.  The storm spirals throughout the ocean and collects more and more moist ocean air.  It spins faster and faster and grows larger and larger! As it gets stronger, it gets rounder and the eye begins to form.  When it reaches speeds of 74 mph or higher, the storm is called a hurricane.  

The Eye of the Storm
~center of the hurricane is known as the eye; here the air is calm, the temperature is warm, and the sun shines
~the spinning winds all around the eye are violent

Damage
When a hurricane reaches the shore, it is out of control at 500 miles wide and 150 mph winds.  Winds damage buildings, peers, power lines, homes, and trees.  Sometimes, a hurricane will cause a tornado to occur as well.  The winds from the tornado cause even more damage.   Hurricanes also cause flooding; they can cause several feet of water to drop each day and ocean waves swell up to sixty feet high!   Rivers and streams can overflow causing destruction to crops, homes, and businesses.   Storm surges are also damaging.  A storm surge is a giant wall of water that is pushed on shore by the wind from the hurricane.  When this bulge in the sea reaches the coast, it causes costal waters to rise 20 feet above normal which produces flooding that destroys many more homes and many more businesses.

How Does a Hurricane End
1.  At sea, they die when they pass over cooler waters
2. Hurricanes need warm, moist air to keep going.  Once a hurricane travels to the inland, it becomes less violent since there is less moist air.  It usually merges into a small rainstorm and eventually dies out.      

Naming a Hurricane
All hurricanes are named in order to keep better track of them.  They are named when they become tropical storms; the names follow the alphabet, so the first storm of each year starts with an A and they are given human names.

Wind Speeds
Hurricanes are grouped according to their wind speeds.   Only two CAT 5s have hit the US in the last 100 years.

Tracking Hurricanes
Tracking hurricanes is important.  People who live in the possible path of the storm need warning time to prepare as much as possible.  Here are some ways the hurricane is tracked:

1. Meteorologists follow storms using pictures of the Earth taken by satellite.  The pictures are taken over many hours and they reveal the direction as well as the speed of the storm. 
2.  Weather planes fly right into the eye of the hurricane to measure the speed of the wind.
3.  Ships measure the heat of the sea around the storm.  This is important because if the hurricane is moving toward warmer water, it will often get stronger. 

Hurricane Season
Where and when  is a hurricane most likely to hit? 
~In the Atlantic Basin- June 1st to the end of November marks hurricane season with the most active hurricanes between August and October.  This region averages 9.7 tropical storms and 5.4 hurricanes each year.
~In the Eastern Pacific- May through October; most active season is May- August   This region averages 16.5 tropical storms and 8.9 hurricanes each year.
~The Northwest Pacific Ocean averages more cyclones than any other region on Earth with 25 tropical storms each year and 16 hurricanes. 
~North Indian Ocean has the least amount of tropical storms (5-6) and hurricanes each year (2-3), but the results of these hurricanes are often worse than any other region.