Name ______

Everybody talks about…the weather. You may have heard the expression, “Everyone talks about the weather, but no one ever does anything about it.” Well, we do talk about weather all the time, because this powerful force of nature affects everything we do. As sophisticated as the modern world is, we are still pretty much at the mercy of the weather. We cancel picnics when it rains and sometimes get a day off from school when it snows. Warm, sunny days and rain help crops grow, but too much of either kills them. A storm like a tornado can cause millions of dollars in damage and take many lives.

Rain, snow, hot sunny days, wind…what creates these and all the other events we call weather? Heat from the Sun.

The Sun heats up the land and water on the Earth’s surface; this heat rises up and warms the atmosphere. All this air movement gives us weather in all its great variety, from the wildest storms of winter to the most pleasant, sunny days of summer.

Weather happens in the atmosphere, a layer of air wrapped around our planet. Almost all our weather happens in the lowest part of the atmosphere called the troposphere. It’s like a gigantic mixer, churning up all the ingredients – air pressure, temperature, wind, and humidity – to make different types of weather.

1 Temperature The land and water on Earth’s surface absorb heat energy from the sun. Some of this heat energy then warms the atmosphere above the surface. The amount of heat that is absorbed by the Earth’s surface and then released into the atmosphere changes from hour to hour and day to day.

The sun is lowest in the sky early in the morning. When the sun is low in the sky, sunlight strikes Earth’s surface at a low angle. The sunlight is spread out so the ground warms up less. At noontime, when the sun is highest in the sky, sunlight strikes Earth’s surface like a more focused beam. The light is more concentrated. Earth’s surface heats up more. A few hours later, much of this heat has warmed the atmosphere. That’s why temperatures are usually highest in mid-afternoon.

Different surfaces heat up at different rates. Grass heats up very slowly and does not hold heat well. That’s why grass feels cool to your bare feet on a hot day. Water heats up slowly, but holds heat longer than grass. Roads, especially black tar roads, heat up quickly and can get very hot on a sunny day. They cool down quickly during the night.

Wind Wind is moving air. Air moves because Earth’s surface is heated unevenly. On a hot summer day at the beach, the land heats up faster than the water. The air above the land becomes warmer than the air above the water. The warmer air above the land rises. It is replaced by cooler air moving in from above the water. This wind is called a sea breeze.

After sunset, the land cools faster than the water. Now the air above the water is warmer than the air above the land. The warm air above the water rises. It is replaced by cooler air moving in from above the land. This wind is called a land breeze.

Wind speed is measured with an anemometer. The wind pushes against the cups A wind vane shows wind and makes them direction. The arrow points spin around. The to the direction the wind is faster the wind is coming from. In this blowing, the faster picture, the wind the cups spin. Weather (Eyewitness video) is blowing from the west, so the arrow points west. 1. The ______changes when sunshine, air, and water interact on the ground and in the sky to produce clouds and wind.

2. Scientists who study the weather are called ______

3. The blanket of air that surrounds Earth: ______

2 4. Moving air that blows from high to low-pressure areas: ______

5. Air has weight, it pushes on things in all directions, and this is called ______

6. Air always moves from ______pressure to ______pressure areas.

7. Energy from the Sun causes liquid water to turn into a gas called ______

8. The change of liquid water into an invisible gas called water vapor: ______

9. The water vapor rises into the atmosphere and cools as it rises, joining with dust or smoke particles along the way. As it cools, the invisible water vapor collects into tiny water droplets that form ______

10. The droplets in clouds keep combining, causing the clouds to ______

11. Eventually, the droplets get so large; they can no longer remain up in the air,

______pulls them down toward the Earth’s surface.

12. When moisture returns to the Earth’s surface it is called ______

13. Precipitation can be in the form of: ______

14. A tool that measures in what direction the wind is moving. ______

15. A tool that measures how fast the wind is moving. ______

16. The ______is a strong, fast-moving river of wind high in the atmosphere that blows from west to east around the world.

17. The never ending process that recycles Earth’s water supply by using energy from the sun.

______

18. A cloud on the ground. ______

19. Thunderheads…these clouds grow very large and dark and they bring storms, heavy wind and lightning:

______

How’s the weather? http://www.brainpop.com/search/search.weml?keyword=weather “Weather”

The answer to this question depends on what kind of air mass is passing over your region. Air masses are large bodies of air. The main characteristics of an air mass are its temperature and humidity. Humidity is a measure of the moisture in the air. An air mass can be cold and dry, warm and dry, cold and moist, or warm and moist. Air masses tend to travel around the globe in big chunks that cover thousands of square miles. Air masses get their particular characteristics from the Earth surface over which they form. Warm, wet areas like

3 the Gulf of Mexico produce warm, humid air masses. Cold, dry areas like northern Canada produce cold, dry air masses. Air masses take on the temperature and humidity of the area over which they form.

Air has mass. Because it has mass, it has weight. Air pressure is the weight of air pressing on everything around it. Air presses on objects from all sides, not just down on them. Air pressure is measured with barometer. When the air pressure changes, you can tell that the weather will change. Rising air pressure means clearer weather is coming. Falling air pressure means unsettled or wet weather is coming.

The air in a high-pressure center is under high pressure, like air in a bicycle tire. High- pressure centers usually bring stable, fair weather, which may be bitter cold and sunny or warm and sunny depending on the season. Clouds and precipitation are usually found in areas where air pressure is low, low-pressure centers. But it doesn’t last forever because air masses are always on the move, bumping into each other as they travel around the globe.

Movement in Air Masses Change Our Weather

When one air mass collides with another, the line that separates them is called a front. Weather changes at fronts. A warm front means a warm air mass has caught up with a cold air mass. A warm front brings steady light precipitation followed by a rise in temperature. A cold front means a cold air mass has caught up with a warm air mass. A cold front brings a sudden change in the weather: heavy precipitation – thunderstorms or snowstorms – and a drop in the temperature.

It’s pretty easy to understand why Hawaii is warm (because it’s near the equator, of course!). But knowing what you do about air masses and fronts, why do you think the Northeast is rather stormy? The Pacific Northwest rainy? The Southwest so dry? The Northeast is stormy because cold air from Canada often collides with warm ocean air from the tropics; the Pacific Northwest is often covered by moist air masses from the Pacific Ocean; the Southwest gets dry air masses from Mexico.

The Jet stream, a band of air high above the Earth, moves air masses from one area to another. This steady worldwide wind blows from west to east 7 to 8 miles above the Earth’s surface. Its speed is usually about 40 miles per hour in the summer and about 80 miles per hour in the winter. The jet stream separates cooler air to the north from warmer air to the south. It usually shifts southward in winter bringing freezing weather as far south as Florida and moves northward in the summer bringing warmer weather up north. When the jet stream dips south over the U.S., it pulls cold air down from Canada. When the jet stream moves north, it pulls warm air up from the Gulf of Mexico.

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http://www.brainpop.com/search/search.weml?keyword=weather “Wind”

Precipitation http://www.brainpop.com/search/search.weml?keyword=water+cycle The atmosphere contains water vapor. When air gets cooler, water vapor condenses. That means it changes to tiny droplets of liquid water. Water droplets clump together to form a cloud.

As more water vapor condenses, the droplets grow larger. When the drops get too large and heavy, gravity pulls them to the Earth’s surface. Water that falls to Earth’s surface is called precipitation. There are different types of precipitation.

Bill Nye Video

1. To forecast a storm, you must know which way the ______is blowing.

2. Sunny, calm weather usually comes with high ______.

3. When a ______shows falling pressure, stormy weather might be coming.

4. The liquid in this weather tool expands consistently when it is heated and contracts consistently when it cools. This tool is used to measure temperature and it is called a ______

5 5. Fahrenheit Scale: Freezing = ______Water will boil at ______

6. Celsius Scale: Water will freeze at ______Water will boil at ______

7. A person who studies the weather is called a ______

8. Some houses have a wind ______on the roof to give the wind direction.

9. This layer of the atmosphere, the ______, is about 8 miles thick; this is where the weather happens.

10. What parts of the Earth are always cold? ______

11. What kind of weather do you find around high-pressure? ______

12. Warm air masses are always forming at this location on Earth: ______

13. What makes weather move around the world? ______

14. Why do seasons occur? Earth’s ______

15. What does an anemometer measure? ______

16. Falling air pressure indicates that ______weather is coming.

17. Rotation or spinning of the Earth gives us ______.

18. Winds are named for where they are coming ______.

19. When the sun is high in the sky the rays are ( spread out OR concentrated ) .

Some plants, like sunflowers, follow the sun. This response is called heliotropism.

In the United States, most thunderstorms happen around Tampa Bay, Florida, where the air and water are always warm.

The most tornadoes on Earth happen in the United States in an area from Oklahoma into northern Texas, called Tornado Alley.

Answer either True or False. If the question if false, fix the statement to make it true.

6 20. ______The wind controls which way weather moves.

21. ______A thermometer tells you air pressure.

22. ______Air pressure is measured with a barometer.

23. ______Low pressure usually means dry, sunny weather.

24. ______Days and nights are caused by Earth’s rotation (spin).

25. ______When air is moving, we call it wind.

26. ______Warm air sinks to the ground.

27. ______The Earth gets its heat from the land and water heated by the Sun.

28. ______A barometer tells you the wind direction.

29. ______The jet stream moves weather around the Earth.

30. ______Cold air is heavier than warm air and it sinks to the ground.

31. ______Thermometers tell you how warm the air is.

32. ______We could live without air.

33. ______Somewhere on Earth, air is always moving.

1. Weather occurs in this part of Earth’s atmosphere: ______

2. A tool used to measure the wind’s speed is called an: ______

3. A tool used to measure the wind’s direction: ______

4. Water vapor in the air is called ______

5. The “push” of air against objects in every direction is called ______

7 6. Land heats up quickly during the day and cools down quickly at night. True or False

7. Water heats up slowly and cools down slowly. True or False

8. Changes in the weather are caused by ______. a. the North and South Poles b. movement of air masses c. changes in temperature

9. Movement of air is called ______

10. Cold fronts cause a sudden change in the weather. True or False

11. Warm fronts are followed by a rise in temperature. True or False

12. When a front passes through a region, the weather ______. a. stays the same b. changes

13. Air masses form over the equator and the North and South Poles because ______. A. cold air is heavier than warm air B. warm air moves toward the poles C. the temperature in these areas is either constantly cold or hot

14. The atmosphere is made mostly of these two gases: ______& ______

Atmosphere Video Bill Nye

air pressure evaporation condensation atmosphere ozone layer day and night barometer photosynthesis precipitation jet stream shooting star seasons troposphere ultraviolet rays

1. The layers of gases that surround a planetary object: ______

2. Earth’s atmosphere is mostly made of: ______& ______

3. The force that air exerts on the Earth’s surface and anything on it: ______

4. An instrument that measures air pressure: ______

5. The lowest part of the atmosphere begins at the Earth’s surface, weather occurs here:

8 ______

6. A band of high speed, high altitude winds usually found in the Earth’s lower stratosphere; these

winds push Earth’s weather around the globe: ______

7. Invisible energy waves from the Sun that are potentially harmful: ______

8. A protective layer of gases in the Earth’s atmosphere that absorbs many of the Sun’s harmful

ultraviolet rays: ______

9. An intense flash of moving light that is caused by small bits of rock and debris crashing into the

atmosphere and burning up in the mesosphere; also called a meteor: ______

10. The process by which green plants create breathable oxygen and sugars from sunlight, carbon dioxide, water, and chlorophyll: ______

11. The conversion or changing of liquid water-to-water vapor: ______

12. The conversion of water vapor, water in its gaseous state, to liquid water: ______

13. Moisture, water that falls from the clouds as rain, sleet, snow, or When it’s so cold hail: ______outside you can see your breath, what you 14. Earth’s tilt and revolution give us are seeing is actually a ______little cloud. When steam rises from a kettle of 15. Earth’s rotation or spin gives us boiling water, it’s a ______cloud you’re seeing. When the fog rolls in, you guessed it…it’s really a cloud.

The air around us is http://www.brainpop.com/search/search.weml?keyword=weather “Clouds” filled with moisture that it soaks up from oceans, lakes, and rivers. As air rises from the warmth of the ground and meets cooler air above, its temperature falls. This causes the moisture to form microscopic droplets of water (the process is called condensation). Clouds are made up of millions 9 of these tiny droplets. Form in the sky opposite the Sun when sunlight shines on falling rain. (Raindrops act as prisms for sunlight, bending rays and separating them into their spectral colors.)

The higher the Sun is in the sky, the lower a rainbow will appear. A Rainy Day, A Snowy Day Have you ever gone to bed at night thinking it’s going to snow? Maybe you’ll get a day off from school. You can spend the day sledding and making snow forts. Then you wake up and, oh no, it’s raining! What happened? It just wasn’t cold enough inside the clouds for snow to form. Whether it’s snowing or raining, the moisture you see falling to Earth began as zillions of tiny water droplets in the clouds.

Why do raindrops keep falling on your head? The answer is gravity. Can you imagine something as 1 tiny as 2,500 of an inch in diameter? That’s the size of a water droplet in a cloud. It’s so small and light it stays afloat. But inside a cloud, droplets keep bumping into other droplets and forming bigger 1 droplets. Once a droplet is of an inch in diameter, gravity pulls it to Earth…as rain or, if it’s cold 250 enough to freeze, as snow.

The next time you’re disappointed because a ball game or another fun activity is rained out, remember that all living things, including us, need rain to survive. Crops like corn and wheat need at least 20 inches of rain or more during a growing season. That’s a lot of water. One inch of rain falling over an acre of ground equals 27,143 gallons of water. In general, that moisture in a foot of snow is equal to the moisture in an inch of rain.

10 Have you ever wondered why hailstorms usually occur in summer? True, hail is moisture that freezes in the clouds, just like snow. But unlike snow, hail forms inside clouds that cause thunderstorms, which occur mostly in warm weather. As the hailstones fall toward Earth, strong winds keep pushing them back up into the colder air, freezing them again with each up-and-down trip. Sometimes these little ice balls can get really big. The biggest one on record is a 1.7 pounder that fell on Coffeyville, Kansas, in 1970.

You’ve probably heard the expression “pure as the driven snow.” Actually, snow isn’t all that pure. Snowflakes form when moisture in clouds clings to tiny bits of dust, clay, sand, and other debris from the Earth and freezes. A snowflake is one of nature’s most beautiful creations. Of the zillions of snowflakes that fall to Earth, each one has six sides, but no two are ever alike.

Keeping an Eye on the Weather

Of course, forecasters don’t just look out the window to prepare the weather report you see on T.V. They use a sophisticated weather information network located all over… and above…the globe. Satellites orbit the Earth constantly. Planes and balloons make daily ascents to gather data. Weather stations in almost every country on Earth contribute data.

As you’ve noticed, forecasters still make mistakes. That’s because a forecast is only a prediction of what’s likely to happen, based on what’s happening now. But nature doesn’t always follow a predictable pattern. So a forecast is only an educated guess, not a guarantee.

Nature gives us a lot of clues about weather conditions.

11 They’re not always foolproof, but people were using these natural weather forecasts long before the Weather Channel went on the air! How many of these do you think really work?

If a groundhog sees its shadow on Groundhog Day (February 2), the weather will remain cold for six more weeks. (No, this is groundhog-wash!)

Pine Cones close up when rain is on the way. (True…check it out sometime.)

A ring around the moon means rain or snow is coming. (Sometimes, since the ring can be caused by thickening moisture in the atmosphere)

Flowers of the morning glory and scarlet pimpernel open when it’s sunny, close when rain is due. (True…sort of. Sometimes they don’t close up until the rain has started to fall.)

“Red sky at night, sailor’s delight. Red sky in the morning, sailors take warning.” (Never been proven to be true.)

Cows lie down when bad weather is coming. (Not very reliable, since cows also lie down when they’re hot or get tired of standing.)

Bill Nye video

1. Water enters the air by ______

2. Moisture in the atmosphere occurs in three states: ______, ______, ______

3. Evaporation is caused mostly by ______from the ______

4. Most of the moisture evaporates from … ______

5. When water evaporates it turns into a gas called ______

6. Water vapor in the air is called ______

7. Which can hold more water vapor, warm air or cold air? ______

8. As water vapor raises up into the atmosphere it (warms up or cools down) ______

12 9. The water vapor molecules cool in the atmosphere and squeeze together to form droplets of ice or water, this

is called ______

10. The gaseous state of water is called ______

11. ______form in the atmosphere when water vapor condenses to form droplets.

12. When the droplets in the clouds get too heavy, they fall back to the Earth’s surface. This is known as ______

13. The four forms of precipitation are: ______, ______, ______, ______

14. The water cycle includes three steps: ______, ______, ______

When you fly in airplanes, your ears pop because of the low pressure in the sky.

Heat from the Sun travels more than 90 million miles through space before reaching Earth.

Many insects, like crickets, become more active when the air is warmer.

Polar Temperate Tropical Arid Very cold winters. Moderate rainfall, Very high rainfall. Very low rainfall. Big Summers are slightly with snow in winter. Very hot and humid changes in temperature warmer, but short. Warm summers and most of the year. between day and night Lots of snow, but cold winters. and between summer and little rain. winter.

How’s the Climate? http://www.brainpop.com/search/search.weml?keyword=weather “Climate”

If you are suffering through a hot, humid summer day, blame the weather. But if …year after year…most summer days where you live are hot and humid, blame the climate.

13 Climate refers to the average weather conditions in a region over a long period of time. For example, near the equator, some hot, steamy tropical rain forests are drenched by about 160 inches of rain per year – every year. (That’s more than 13 feet!) in Las Vegas, Nevada, on the other hand, the average rainfall per year is around four inches. In Antarctica, temperatures are low throughout the year, year after year. They average -70F! However, in Montreal, Canada, the average temperature in January is 13F, while in July it’s 69F!

Climate varies widely all over the world. Because of this, scientists divide the Earth into different climate zones. Conditions aren’t exactly the same all over a specific climate zone, but places in a zone share certain characteristics, like extremely low temperatures or very high rainfall.

Climate affects many aspects of your life, from the clothes you buy to the outdoor sports you play to which plants and animals live near you.

Q: Which animal can survive in any climate?

A: You… and all the other humans on Earth. Our bodies react in certain ways (like shivering) to withstand the cold and in other ways (like sweating) to withstand the heat. But our main survival advantage comes from our brains. We use our brains to invent things that help us remain comfortable when it gets too hot or cold and too wet or dry – like air conditioners and fleece jackets.

Hot? Cold? We’re Flexible! Human bodies can become acclimatized, or used to, levels of extreme cold and heat. If you visit someplace that’s hotter or more humid than you’re used to, you’ll feel uncomfortable at first. But after a week or so, your body will adjust. You’ll start to sweat more, and your temperature won’t rise as much when you exercise. Our bodies’ ability to adapt is one of the main reasons human beings can live in so many different climates.

Will it rain? That’s the question on most people’s minds when they check the weather report (unless it’s really cold out, and they are looking for snow). Watching weather forecasts on TV, you see lots of Hs and Ls and bumpy lines on the weather maps. You also hear plenty of strange phrases like “dew Point” and “barometric pressure.”

To understand weather terms, it’s important to know that its atmosphere - an envelope of air about a thousand miles deep, surrounds Earth. The atmosphere contains invisible gases such as nitrogen and oxygen. It also holds the water vapor that makes rain and snow.

14 About 99% of all weather takes place within the lowest 11 miles of the atmosphere, called the troposphere. The Sun’s heat keeps gases there churning all the time. That makes a weather forecaster’s job pretty tricky.

Fronts A front is the boundary between two masses of air that have different temperatures and levels of humidity (moisture content). Fronts cause storms. Cold air is heavier than warm air. So when a cold front moves in, the cold air wedges underneath the warm air, forcing it to rise. This causes clouds to form and produces rain or snow. A warm front coming in rides up over the cold air. Again clouds form and rains come.

http://www.brainpop.com/search/search.weml?keyword=weather “Thunderstorms” Humongous Hurricanes Dark clouds fill the sky. It’s the middle of the day, but it looks like night. The wind howls. Rain pelts the ground so hard that holes form in the mud. Tree branches bend and crack. Whole trees are uprooted and crash down. Store windows break. The roofs of buildings sail through the air. Electric wires send out sparks and dangle dangerously from broken utility poles. Signs fly across highways. Water floods the streets. It is no time to be outdoors, that’s for sure. You are in the middle of a hurricane – the largest, fiercest storm of nature. How do these storms start, and how can we protect ourselves from them?

Hurricanes begin as clusters of thunderstorms that spiral and grow into one giant storm. Hurricanes feed on warm moist air rising from the ocean near the equator. Warm water evaporates (turns into water vapor) from the surface of the ocean and rises. As it rises, it cools. This causes the water vapor to condense (to squeeze together) forming thunderclouds

15 called cumulonimbus clouds. Strong winds in the atmosphere cause these clouds to swirl. A cumulonimbus is a very large thunderstorm cloud that extends to a great height, over 50,000 feet! Once these clouds form, the first stage of hurricane development has begun. It gets bigger and bigger as winds from the continent of Africa blow the storm westward, picking up more warm moisture. When the wind reaches 74 mph, the storm is called a hurricane. Why don’t hurricanes ever form in Kansas, Oregon, or Vermont? Why do they always start in the tropics? It’s because an area of the tropics that lies between five degrees north and five degrees south latitude of the equator has ocean waters of at least 80F over a large area. This warm moist air is “food” for the Hurricane.

The storms that form in the Atlantic Ocean are called hurricanes, while those that form in the northwestern Pacific Ocean are called typhoons. Storms that form over the Indian Ocean are called cyclones. Australians call these storms willy-willies. Meteorologists call all of these storms tropical cyclones. Tropical means the storms are formed in areas of oceans near the equator. No matter what the storms are called, on average, about 80 of them occur worldwide each year.

Tornado Terrors

A tornado, or twister, is a spinning column of air that sucks up everything in its path. During thunderstorms, hot air rises and meets cold air. If the air currents whirl around each other, then a deadly twister is born! Tornadoes are by far the most destructive storms on Earth. Winds in the whirling black column called a funnel cloud can exceed 300mph. The funnel cloud is like a giant vacuum cleaner, picking up cars, houses, and everything else in its path.

After a tornado has passed, people notice some strange things. Sometimes, for instance, pieces of wheat are rammed through trees like arrows, or a school of fish ends up in someone’s front yard.

About 75% of all tornadoes occur in the United States; that’s tornado alley. Anyone living in the areas between Texas and Illinois can expect an average of 750 twisters a year!

That’s Weird! A tornado on a sea or lake is called a waterspout. It’s a twisting column of spray and water vapor that sways over the waves 16 like a snake. Sailors in ancient times thought that waterspouts were sea monsters who had come to devour their ships.

NEVER STAND UNDER a tree or in an open field during a lightning storm.

Where does lightning come from? Lightning is made inside a huge, dark storm cloud, called a cumulonimbus. Inside a storm cloud, water droplets and ice crystals rub together. This rubbing makes electricity, which builds up and builds up. Suddenly, it surges out of the cloud in the huge spark that we call lightning.

And thunder? Thunder is made by lightning. A lightning bolt is amazingly hot – four times hotter than the surface of the Sun. air around the bolt heats up so quickly that it expands with a mighty rumble. This creates a massive roll of thunder.

Why the flash before the boom? Thunder and lightning set off together. But light travels so fast that lightning speeds off. It takes five seconds for sound to travel a mile. Lightning always arrives first. This is why you see the flash of lightning before you hear the boom of thunder. When you see the lightning flash, start counting the seconds until you hear the thunderclap. Divide the number of seconds by five to find out how many miles away the storm is.

http://www.brainpop.com/search/search.weml?keyword=weather “Tornadoes”

1. Tornadoes only happen in the daytime. ______

2. Most tornadoes hurt people. ______

3. Tornadoes last for many hours. ______

4. The United States has the most tornadoes. ______

5. Tornadoes come from severe thunderstorms. ______

6. Some people call tornadoes “twisters.” ______

7. It’s OK to stay outside during a tornado. ______

8. Tornadoes are bigger than hurricanes. ______

17 9. The F-Scale measures how slow a tornado is going. ______

10. Mobile homes are safe from tornadoes. ______

About 1,000 tornadoes happen every year in the United States.

Mobile homes don’t attract tornadoes, but they are more damaged by tornadoes than regular homes.

While most tornadoes don’t hurt people, in 1925, a tornado killed nearly 700 people. It lasted more than three hours as it moved over 200 miles across three states.

Big tornadoes are not always stronger than smaller tornadoes.

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