What is Weather?

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What is Weather?

• Weather - is the condition of air on earth at any
  given time or place- whether its warm or cold,
  dry or wet, blowing or calm.

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Predictable Patterns of Weather

• Precipitation depends on the temperatures of the
  ground and atmosphere.
• Wind speed and direction help determine unequal
  heating or air masses, and is also related to air
  pressure differences.
• Temperature Affected by many factors
• Cloud Cover caused by pressure systems and can
  change precipitation and temperature.
• Weather Smart Forecasting and Weather
  Instruments   (United Streaming)

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REASONS FOR SEASONS

• THE EARTH IS TITLED ON AN AXIS AT THE NORTH AND
  SOUTH POLE AND THIS CREATES THE SEASONS.
• THE IMAGINARY LINE RUNNING THROUGH THE MIDDLE OF
  THE EARTH IS CALLE D THE EARTHS AXIS/EQUATOR.
• ANOTHER REASON WE HAVE DIFFERENT SEASONS IS
  BECAUSE THE EARTH MOVES AROUND THE SUN SO THE
  NORTH POLE IS EITHER FACING TOWARD THE SUN OR
  AWAY FROM THE SUN.
• THE EARTHS TILT CAUSES DIFFERENT AMOUNT OF
  SUNLIGHT TO REACH THE EARTH AT DIFFERENT TIMES IN
  THE YEAR. THE NORTHERN HEMISPHERE GETS MORE
  DIRECT SUNLIGHT IN THE SUMMER BECAUSE THE
  SOUTERN HEMSPHERE IS TITLTED AWAY FROM THE SUN
  THEY ARE HAVING THEIR WINTER.
• NEAR THE EQUATOR, THE EARTH DOESNT HAVE WINTER
  OR SUMMER. THE WEATHER BARELY CHANGES AT ALL.

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REVOLUTION AND ROTATION

• REVOLUTION EARTH MOVING IN A PATH AROUND THE
  SUN, RESULTING IN ONE EARTH YEAR.
• ROTATION THE EARTH SPINNING AROUND EVERY 24
  HOURS, RESULTING IN DAY AND NIGHT.

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Weather and Geography

• There are many geography factors that affect
  weather and climate. They include
• Latitude
• Altitude
• Winds
• Distance from the sea
• Urbanization/living in the city

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Latitude The distance from the equator can
determine weather and climate.

• As you move closer to the equator the temperature
  increases. The farther away you are from the
  equator the temperature decreases. This is due to
  the suns rays.

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Earth has three major climate zones. These zones
are determined by latitude, or their position on
Earth in relation to the equator
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Altitude The farther up you go the temperature
decreases and it gets cold. Air is less dense and
cannot hold the heat.

• Notice that there is snow at the top of this
  mountain. The higher up you go the colder it
  becomes. Therefore, mountain regions have colder
  temperatures.

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Distance from the sea and bodies of water
The closer you are to the ocean the cooler the
temperature.Water warms and cools much more
SLOWLY than land.The temperature of water does
NOT change as quickly as the temperature on land
does.Land near water has milder weather because
of the waters influence.

• Thats why cities like Wilmington have cooler
  temperatures then cities like Raleigh.

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Bodies of Water

• Lakes help moderate the temperatures on the land
• The nearby water causes an increase in moisture
  in the air, so in the winter these areas
  experience heavy snowfall.

Lake Effect Snow
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Urbanization Living near or in a city also
affect the temperature.

• Cities usually have warmer and rainier weather
  because it is surrounded by pavement , larger
  building and factories.

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Winds Depending of where the winds came from,
they can increase or decrease temperature.
Example If cold winds blow, especially from the
north, temperature is colder. If warm winds blow,
usually from the south, the temperature is
warmer.
When wind blows against a mountain it causes the
air to rise and cool. When it flows over the
mountain and down the other side it causes the
air to become cooler and takes the moisture from
the clouds to create rain. This is called the
rain shadow effect
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Clouds

• Clouds consist of billons of tiny water droplets
  (and even ice crystals) floating in the sky and
  clouds form when rising air cools and the
  moisture in it condenses to water droplets.

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Three things are needed for clouds to form
evaporation, cooling, and condensation

• Clouds can be named by their appearance or how
  they look and where they are located in the sky.

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Types of Clouds

• Cirrus clouds are high, thin, and wispy white
  clouds that are made of tiny ice pieces and they
  bring nice weather and usually means a change in
  the weather.
• Stratus are flat gray clouds which are layered
  and low to the ground. When stratus clouds are
  low to the ground, it creates fog. These clouds
  usually mean rain is coming.
• Cumulus are big, white, puffy , clouds that
  look like cauliflower. They bring fair weather on
  sunny days.
• Cumulonimbus thick, dark, tall puffy
  thunderheads clouds means heavy rain and
  thunderstorms.

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The Cloud Song (tune of The Farmer and the Dell
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• Altitude and Cloud Formation
• Clouds can also be described by the
  altitude/height at which they form. The prefix
  cirro means clouds that form high in the sky.

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• The prefix alto are Clouds that form in the
  middle of the sky . A stratus cloud that forms at
  a middle altitude is called an altostratus cloud.
  
• Alto cumulus alto stratus

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• The prefix strato are clouds that form at low
  altitudes or low in the sky so a cumulus cloud
  that forms at a low altitude is called a
  stratocumulus cloud.
• Nimbostratus

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Guess the Clouds

• These clouds form when the wind is strong

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Brings fair weather
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Brings thunderstorms
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Another word for fog
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Air Mass

• A large body of air that has the same temperature
  and level of humidity throughout.
• cool air masses where the land temperature is
  cool
• warm air masses form over the land that is warm.
• dry air masses form over dry areas
• wet air masses form over wet areas like oceans.

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Fronts

• When air masses meet, a boundary called a front
  is formed, preventing the masses from mixing.
• Two different types of air masses do not mix,
  because of the different densities
• Warm is less dense than cold air.
• When warm air and cold air meet, warm air will
  rise above cold air.

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Cold Front

• Cold Front What is it? At the cold front, the
  cold air cuts underneath the warm air and forces
  the warm air up a much steeper angle. At cold
  fonts the air is cooled quickly and forms a
  narrow band of thick cumulonimbus clouds. These
  produce heavy rain, snow or precipitation.

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Cold Fronts bring

• Heavy rains
• Thunderstorms
• Sometimes snow

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Warm Front

• A warm air mass moves up and over a cold air
  mass. Rainy, drizzly weather. Often followed by
  clear, warm weather

Direction of Front
Warm Air
Cold Air Mass
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Occluded Front

• Two cold air masses move toward each other,
  warmer air between is pushed up and brings Cool
  temperatures, plenty of rain and snow.

Warm Air
Cold Air Mass
Cold Air Mass
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Stationary Front

• When a warm and cold air mass meets, but neither
  has enough energy to push against each other.
  Many days of overcast, rainy weather

Cold Air Mass
Warm Air
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Cold Front A cold air mass moves under a warm
air mass pushes the warm air upward. .Cold
fronts bring heavy rain and thunderstorms and
cold weather.
Warm front forms when warm air bumps with colder
air. This front brings rainy, drizzly weather,
often followed by warm, clear weather .
Occluded front forms when a warm air mass is
caught between two cold air masses. This brings
cool temperatures and lots of rain and snow.
Stationary front occurs when a warm air mass and
a cold air mass meet.. This brings many days of
overcast and rainy weather.
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Breezes affect the weather too

• Valley breeze The Sun warms the air above the
  valley during the day. The warm air rises and
  flows up the mountain.
• Mountain breeze At night the mountains cool down
  faster than the valleys do because of their
  elevation. The cool air sinks and flows down the
  mountain.
• Sea breeze The cool, high-pressure air over the
  ocean that flows toward land
• Land Breeze the movement of air created by cool
  air over land moving toward the ocean.

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Sea Breeze

• During the day, air over the ocean is cool. Cool
  air masses form over areas of high pressure. Air
  over the land is warmer, and as it rises, it
  creates an area of low pressure.
• The cool, high pressure air over the ocean now
  flows toward the land, creating a sea breeze.

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Sea Breeze
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Land Breeze

• At night, the air over the ocean is warmer than
  the air over the land. (WHY?)
• The warm air over the ocean rises creating an
  area of low pressure.
• The cool air over the land forms an area of high
  pressure and moves toward the ocean, producing a
  land breeze.

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Land Breeze
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Mountain Breeze

• At night, the mountains cool down faster than the
  valleys do, because of their elevation.
• The cool air SINKS and flows down the mountain,
  causing a mountain breeze.

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Mountains affect

• Patterns of Rainfall
• Rain Shadow Effect

Wet Side
Dry Side
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Which breeze am I?
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Measuring Atmospheric Conditions and Air Pressure

• The weather changes because the atmosphere is
  constantly changing. Sometimes the air is cold
  and sometimes its warm. As air warms, its
  weight, or air pressure, lessens or gets lighter.
  Air pressure is the weight of the air pressing
  against everything on Earth. Air pressure goes
  from high pressure to low pressure.
• A low pressure system is a whirling mass of warm,
  moist air that generally brings stormy weather
  with strong winds. When viewed from above, winds
  spiral into a low-pressure center in a
  counterclockwise rotation in the Northern
  Hemisphere. A low pressure system is represented
  as a big, red L
• A high pressure system is a whirling mass of
  cool, dry air that generally brings fair weather.
  When viewed from above, winds spiral out of a
  high-pressure center in a clockwise rotation in
  the Northern Hemisphere. These bring sunny skies.
  A high pressure system is represented as a big,
  blue H.

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Low Pressure- air circulation, is
counterclockwise and Storms are caused by rising
warm, moist air
High Pressure air circulation is clockwise and
sunny conditions
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Why is bad weather usually associated with low
pressure and good weather with high pressure?

• In an area of low pressure, air from neighboring
  areas (which are of higher pressure) moves in. It
  has nowhere to go but up. Upward movement of air
  causes condensation of water vapor, leading to
  the development of cloud and rain. So, a low
  pressure area usually associated with bad
  weather.
• In contrast, in an area of high pressure, the air
  at low levels spreads outward and air descends
  from aloft. Downward motion warms up the air and
  is favorable for evaporation. Hence, a high
  pressure area usually has fine and dry weather.
  Air descends in high pressure area and rises in
  low pressure area.

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Warm Air and Cold Air Meeting Forms RainCool
air sinks and forms an area of high pressure.
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Warm Air Rising Above a Cold Front Warm air
rises and creates an area of low pressure.
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Barometric Pressure
Barometers measure air pressure. If air pressure
changes, it means the weather is probably going
to change, too. Rising barometric pressure is If
the air pressure changes from low to high
pressure, the barometric pressure is rising. The
weather will probably be nice and clear. Falling
barometric pressure is I f the barometric
pressure changes from high to low pressure, it is
falling. This means a storm might be coming.
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Jet Streams

• Jet streams are narrow bands of fast moving air
  about eight miles above the Earth's surface.
• They are among the most powerful forces on the
  planet. Jet streams affect surface weather.
• Wind is the movement of air from a high pressure
  area to a low pressure area.
• Winds curve because of Earth's rotation.
• In the temperate zone, warm and cold air clash
  along weather fronts.

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Coriolis Effect

• Winds do not simply blow in straight lines from
  north to south. Instead, they are bent by the
  spinning of the Earth To the right north of the
  equator, and to the left in the south.
• The Coriolis Effect bends every wind on Earth,
  resulting in a distinct pattern of winds around
  the world

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Trade Winds and Westerly Winds

• Trade Winds Blow mainly from the east for
  example the steady winds blowing towards the
  equator from the subtropics.
• These are known as trade winds because they were
  used by sailing ships carrying trading goods
  around the world.
• Westerly Winds is a wind systems blowing from the
  west and moving the winds to the east

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Prevailing Winds
Between thirty and sixty degrees latitude, the
winds that move toward the poles appear to curve
to the east. Because winds are named from the
direction in which they originate, these winds
are called prevailing westerlies. Prevailing
westerlies in the Northern Hemisphere are
responsible for many of the weather movements
across the United States and Canada. 
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• What are the polar easterlies?At about sixty
  degrees latitude in both hemispheres, the
  prevailing westerlies join with the polar
  easterlies to reduce upward motion.
• The polar easterlies form when the atmosphere
  over the poles cools. This cool air then sinks
  and spreads over the surface.
• As the air flows away from the poles, it is
  turned to the west by the Coriolis effect. Again,
  because these winds begin in the east, they are
  called easterlies. 

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The Doldrums

• The Doldrums are an area of low pressure
  occurring where the trade winds meet along the
  equator.
• Winds here are usually calm or very light and so
  ships would avoid the area because they would
  only be pushed along very slowly.

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What is the Difference Between El Nino and La
Nina?

• La Nina - (Lah Nee-Nyah) is the cooling of water
  in the Pacific Ocean.
•  Snow and rain on the west coast
• Unusually cold weather in Alaska
• Unusually warm weather in the rest of the USA
• Drought in the southwest
• Higher than normal number of hurricanes in the
  Atlantic

• El Nino - (El Nee-nyo) is the warming of water in
  the Pacific Ocean.
• Rain and flooding along the Pacific coast
• Warm water disrupts food chain of fish, birds,
  and sea mammals
• Tornadoes and thunderstorms in southern US
• Fewer than normal hurricanes in the Atlantic

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Weather Tools

• Hygrometer measures the amount of humidity or
  moisture is in the air
• Wind Vane measures wind direction

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Other Weather Tools that help Predict the Weather

• Anemometer measures wind speed.
• Thermometer measures temperature outside.
• Rain Gauge measures the amount of rain fall.

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Weather Symbols
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Great Weather website for kids!

• http//www.weatherwizkids.com/weather-forecasting.
  htm

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Review Questions 5. E.1.1

• 1. Which is generally considered to
  be least important in determining the local
  weather conditions of an area?
• A. Landforms
• B. Wind speed
• C. Precipitation
• D. Temperature

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• 2. Which conditions will result in high winds?
• A. large differences in air pressure
• B. heavy rains over several days
• C. increase in evaporation rates
• D. presence of cirrus clouds

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• 3. Which will be the effect of a warm front
  moving into an area?
• A. Light precipitation will begin as the front
  arrives and remain after the front is gone.
• B. Light precipitation will begin as the front
  arrives and clear after the front is gone.
• C. Skies will clear as clouds are moved by the
  front and grow cloudy after the front is gone.
• D. Skies will clear as clouds are moved by the
  front and remain clear after the front is gone.

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• 4. How would weather conditions in an area change
  if a high pressure system replaced a low pressure
  system?
• A. The area would become more stormy and rainy.
• B. The area would become more humid and warmer.
• C. The area would become cooler with less
  humidity.
• D. The area would become warmer with strong
  winds.

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• 5. What type of weather is usually found in low
  pressure areas?
• A. hot and dry
• B. wet and stormy
• C. cold and snowy
• D. sunny and humid

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  Air Pressure  Clouds in the Sky     Temperature(in degrees Fahrenheit)
City W   High  Yes  18
City X  High  No  31
City Y  Low  No  28
City Z  Low  Yes  43
6. Based on the information in the table, in
which city will it most likely rain? A. City W
c. City Y B. City X
d. City Z c. City y

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• 7. How does the ocean affect the weather along
  the coast of North Carolina?
• A. It causes less wind along the coastal areas
  than areas farther inland.
• B. It causes less severe weather along the
  coastal areas than areas farther inland.
• C. It causes less change in temperature along the
  coastal areas than areas farther inland.
• D. It causes more frequent changes in humidity
  along the coastal areas than areas farther inland

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• 8. Which has the greatest effect on the
  temperature of a region?
• A. Which has the greatest effect on the
  temperature of a region?
• B. the amount of rainfall it gets
• C. the amount of humans it has
• D. the amount of sunlight it gets

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• 9. Which best explains why weather across the
  United States continually changes?
• A. the movement of air from the Atlantic Ocean
• B. the movement of high and low air pressure
  masses
• C. the distance between the United States and the
  Equator 
• D. the distance between the Arctic Circle and the
  United States

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• 10. When a low pressure system moves into North
  Carolina, which kind of weather will most
  likely occur?
• A. cold and dry 
• B. fair and sunny
• C. clear and humid 
• D. rainy and windy 

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• 11. Throughout the year, there is usually some
  wind blowing at the beach during the day and
  night. What is the cause of these winds?
• A. air flowing down mountains to the ocean
• B. differences in the humidity over land and
  ocean
• C. differences in the temperature of land and
  ocean
• D. air flowing from the upper parts of the
  atmosphere

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• 12. Which has the greatest effect on temperature
  in parts of the United States with a moderate
  climate?
• A. geographic location
• B. daily rainfall amounts
• C. changes in humidity levels
• D. number of large cities in the area

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• 13. Which would be the best way to collect data
  from a rain gauge?
• Check and record the data once a week.
• Check and record the data every day, at the same
  time each day.
• Check and record the data for 3 days, then
  estimate what the next readings will be.
• Research the rainfall history of the area, then
  estimate how much rainfall may occur.

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• 14. What type of cloud is responsible for
  thunderstorms?
• cirrus
• cirrostratus
• cumulus
• cumulonimbus

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• 15. Which type of cloud is most often visible
  during fair weather?
• altostratus
• cirrus
• cumulonimbus
• stratus

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• 16. Which clouds indicate precipitation?
• Cirrus
• Stratus
• Nimbus
• Cumulus

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• 17. A scientist is collecting data over time
  using a barometer. What trends could best be
  revealed from the data?
• changes in cloud cover
• changes in temperature
• changes in air pressure levels
• changes in precipitation levels

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• 18. Why do scientists collect data about the
  amount of water vapor in the air?
• to determine humidity levels
• to monitor evaporation rates
• to predict wind speed and direction
• to determine atmospheric pressure

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• 19. A student observes and records cloud cover
  throughout the day. Which event could the
  student most likely predict if they observe
  increasing cumulonimbus clouds?
• The area will have sunny skies.
• The area will have precipitation.
• The area will have cooler temperatures.
• The area will have warmer temperatures.

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• 20. Which is the most useful data scientists can
  use to help determine drought conditions?
• weather radar and satellite pictures
• wind speed records and temperature records
• rainfall measurement and barometric pressure
• rainfall measurement and lake and river water
  levels

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• 21. Today the weather is rainy and warm. The
  weather forecast is that it will be cold during
  the night. Which will most likely be observed
  while the front moves through the area?
• an increase in humidity
• dry and clear conditions
• winds blowing from the south
• an increase in thunderstorms

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• 22. In the morning, Carlos noticed that the air
  pressure reading on the barometer was beginning
  to drop. What kind of weather can he most
  likely expect in the evening?
• The weather will be cloudy with a chance of rain.
  
• The weather will be warmer with clear skies.
• The weather will be clear and windy.
• The weather will be sunny and cool.

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• 23. The forecast said a high pressure system will
  arrive this weekend. Benito and his friends want
  to go camping. Should they plan to go?
• Yes, the high pressure system will create clear,
  sunny skies.
• o, the high pressure system will create storm
  clouds and tornadoes.
• Yes, the high pressure system will create skies
  filled with cumulus clouds.
• No, the high pressure system will increase
  humidity and cause rain clouds to form.

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• 24. A thunderstorm moved through Raleigh. Which
  graph best shows a barometers data
  before, during, and after the storm?

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• 25. Which describes the direction of prevailing
  westerlies or global winds?
• east to west
• west to east
• south to west
• west to south

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• 26. Which best explains what type of weather the
  Gulf Stream usually brings to North Carolina?
• increased wind speed
• increased air pressure
• increased temperature
• increased evaporation

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• 27. What guides the cold arctic air that enters
  North Carolina in the winter months?
• jet stream
• trade winds
• subtropical air mass
• maritime polar air mass

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• 28. Global atmospheric patterns are responsible
  for most local weather. Which causes these
  patterns to exist?
• mountain ranges
• greenhouse gases
• holes in the ozone layer
• unequal heating of Earth

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• 29. Which conditions are most likely to create a
  hurricane off the coast of North Carolina?
• Cool water temperatures and a tropical storm
  moving from the northeast.
• Cool water temperatures and a tropical storm
  moving from the southeast.
• Warm water temperatures and a tropical storm
  moving from the northeast.
• Warm water temperatures and a tropical storm
  moving from the southeast.

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• 30. Which winds are most responsible for the cold
  weather that occurs in North Carolina during the
  winter?
• maritime polar
• continental polar
• maritime tropical
• continental tropical

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• 31. Which explains the high precipitation levels
  in areas near the equator?
• The equator has very little wind, which causes
  rain-filled clouds to remain still for longer
  periods of time.
• The equator has stronger winds that cause clouds
  filled with precipitation to burst, resulting in
  precipitation.
• At the equator, warmer conditions create an
  increase in evaporation. Evaporation leads to
  more precipitation.
• At the equator, warmer conditions create a
  decrease in evaporation. Less evaporation leads
  to more precipitation.

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• 32. What is described by air that is constantly
  moving because of the differences in water
  temperature and land temperature?
• tides
• hurricanes
• sand dunes
• sea breezes

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• 33. How does a large body of water usually affect
  weather conditions on nearby land?
• It causes the weather to be dryer in the winter.
• It causes the weather to be colder in the winter.
  
• It causes the weather to be warmer in the winter.
  
• It causes the weather to be less severe in the
  winter.

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• 34. Which direction does air circulate into low
  pressure zones in the Northern and Southern
  Hemispheres?
• counterclockwise in the Northern Hemisphere,
  clockwise in the Southern Hemisphere
• clockwise in the Northern Hemisphere,
  counterclockwise in the Southern Hemisphere
• clockwise in the Northern Hemisphere, clockwise
  in the Southern Hemisphere
• counterclockwise in the Northern Hemisphere,
  counterclockwise in the Southern Hemisphere

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• 35. What determines the direction in which air
  masses flow across the United States?
• the Gulf of Mexico
• the Atlantic Ocean
• the heat from the sun
• the rotation of Earth

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• What best describes why winds at the beach change
  direction between day and night?
• Because the temperature over the land and over
  water change
• Because warms air over land sinks and stays in
  place over land
• Because cool air rises and is replaced by warm
  air from the ocean
• Because cool air sinks and stays over land

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• Which will most likely result from a low-pressure
  weather system?
• Warm temperature
• Cloudy conditions
• Clear conditions
• Cool temperatures

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• 39.Which is the best explanation for how air
  masses move across the United States?
• The prevailing westerlies move air masses from
  weat to east across the United States but may be
  deflected by the jet streams.
• The trade winds move air masses from west to east
  across the United States.
• The jet stream moves air masses from Pacific
  Ocean across the United States
• The warm air of the Gulf Stream causes air masses
  to move from the Atlantic Ocean to the Pacific
  Ocean.

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• 40. Which has the greatest effect on wind speed?
• Precipitation
• Cloud cover
• Wind direction
• Air pressure

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• 41. The weather forecast indicates that a warm
  front will be moving into the area in the next 24
  hours. Which type of weather will most likely
  result?
• Clear skies and cold temperature
• Clear skies and hot temperature
• Cloudy skies and rainy weather
• Heavy snow and ice

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• 42. What is the cause of rising surface
  temperatures of the Pacific Ocean, drought in the
  western United States, and flooding on the
  Pacific coast of South America?
• The Gulf Stream
• The jet stream
• La Nina
• El Nino

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• 43. What will most likely result when the jet
  stream moves south of North Carolina?
• North Carolina will experience tropical weather
  conditions.
• North Carolina will experience hot, dry weather
• North Carolina will experience mild weather
• North Carolina will experience cold weather

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• Which best describes a characteristic of the jet
  stream?
• Its forms a boundary between a cold air mass and
  a warm air mass
• It creates the high winds around the eye of a
  hurricane
• It forces the hot air along the equator to rise
  to areas in the North America
• It causes high pressure air masses to rotate
  clockwise.

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• On a cloudy day, the local weather forecaster
  predicts that high-pressure system will be moving
  into the area in the next 24 hours. Which
  weather conditions will this system most likely
  bring to the area?
• Stormy
• Sunny
• Snowy
• hot