Air Masses and FrontsAir Masses and Fronts Air masses are classified according to Air masses are classified according to

temperature and humiditytemperature and humidity 4 major types of air masses:4 major types of air masses:

Maritime tropical: form over the ocean and bring in Maritime tropical: form over the ocean and bring in warm, humid airwarm, humid air

Continental tropical: form over dry land areas and Continental tropical: form over dry land areas and bring in hot, dry air (form only in the summer)bring in hot, dry air (form only in the summer)

Maritime polar: form over the ocean and bring in Maritime polar: form over the ocean and bring in cool, humid aircool, humid air

Continental polar: form over land and bring in cool Continental polar: form over land and bring in cool or cold airor cold air

Fronts form when air masses meet and do not Fronts form when air masses meet and do not mix because of densities (like oil and water)mix because of densities (like oil and water)

Air Masses and FrontsAir Masses and Fronts 4 major types of fronts:4 major types of fronts:

Cold front: forms when cold air moves underneath Cold front: forms when cold air moves underneath warm air, forcing the warm air to rise (picture pg. warm air, forcing the warm air to rise (picture pg. 499) – how does this affect local weather?499) – how does this affect local weather?

Warm front: forms when warm air moves over cold air Warm front: forms when warm air moves over cold air (picture pg. 500) – how does this affect local weather?(picture pg. 500) – how does this affect local weather?

Stationary front: when warm and cold air masses Stationary front: when warm and cold air masses meet, however aren’t strong enough to move the meet, however aren’t strong enough to move the otherother

Occluded Front: forms when a cold air mass and a Occluded Front: forms when a cold air mass and a cool air mass come together, the warm air caught cool air mass come together, the warm air caught between them is forced upward.between them is forced upward.

What is the difference between a cyclone and What is the difference between a cyclone and anticyclone?anticyclone?

Air Masses and FrontsAir Masses and Fronts What two main characteristics are used to What two main characteristics are used to

classify air masses?classify air masses?

What is a front? Name and describe the 4 types.What is a front? Name and describe the 4 types.

What is a cyclone? What type of weather does it What is a cyclone? What type of weather does it bring?bring?

Why do maritime polar air masses have more Why do maritime polar air masses have more effect on the West Coast than the East Coast?effect on the West Coast than the East Coast?

Classify the 4 types of air masses according to Classify the 4 types of air masses according to whether they are dry or humid.whether they are dry or humid.

StormsStorms Thunderstorms form within large Thunderstorms form within large

cumulonimbus clouds, or thunderheads (this is cumulonimbus clouds, or thunderheads (this is when warm, humid air rises rapidly)when warm, humid air rises rapidly) These produce strong upward and downward winds These produce strong upward and downward winds

and often occur in spring and early summer – late in and often occur in spring and early summer – late in the afternoon when the ground is warm.the afternoon when the ground is warm.

During the storm, positive and negative electrical During the storm, positive and negative electrical charges build up in clouds. The release of this charges build up in clouds. The release of this energy is lightning.energy is lightning.

Lightning jumps within clouds, between clouds or to Lightning jumps within clouds, between clouds or to the groundthe ground

The lightning bolt produces thunder – how does this The lightning bolt produces thunder – how does this happen?happen?

To remain safe during thunderstorms, avoid To remain safe during thunderstorms, avoid touching metal objects because they can conduct touching metal objects because they can conduct electricity from lightning into your bodyelectricity from lightning into your body

StormsStorms Tornadoes develop in low, heavy Tornadoes develop in low, heavy

cumulonimbus clouds – why do these clouds cumulonimbus clouds – why do these clouds sound familiar?sound familiar?

These often occur in spring and early summer – late These often occur in spring and early summer – late in the afternoon when the ground is warm.in the afternoon when the ground is warm.

The safest place to be during a tornado is in the The safest place to be during a tornado is in the basement of a well-built buildingbasement of a well-built building

What is the difference between a tornado watch and What is the difference between a tornado watch and a tornado warning?a tornado warning?

StormsStorms Hurricanes form over warm water as a low-Hurricanes form over warm water as a low-

pressure area or tropical disturbance and gets pressure area or tropical disturbance and gets its energy from the warm, humid air at the its energy from the warm, humid air at the ocean’s surfaceocean’s surface

Winds get stronger as the eye approaches, however Winds get stronger as the eye approaches, however the eye of the storm is very calmthe eye of the storm is very calm

These are the longest lasting stormsThese are the longest lasting storms

Describe the damage that can occur from hurricanes Describe the damage that can occur from hurricanes – what is a storm surge?– what is a storm surge?

How do you remain safe during a hurricane?How do you remain safe during a hurricane?

StormsStorms Describe a winter storm. What is lake-effect snow? Describe a winter storm. What is lake-effect snow?

How do you remain safe?How do you remain safe?

What weather conditions are most likely to cause What weather conditions are most likely to cause thunderstorms and tornadoes?thunderstorms and tornadoes?

What is the most common path for the hurricanes that What is the most common path for the hurricanes that strike the United States?strike the United States?

What safety precautions should you take if a tornado What safety precautions should you take if a tornado is predicted in your area? If a hurricane is predicted in is predicted in your area? If a hurricane is predicted in your area?your area?

In the winter, cool, humid air from the Pacific Ocean In the winter, cool, humid air from the Pacific Ocean blows across the cold land of southern Alaska. What blows across the cold land of southern Alaska. What kind of storm do you think this causes?kind of storm do you think this causes?

FloodsFloods The most dangerous weather-related event in The most dangerous weather-related event in

the US. Floods cause almost half of weather the US. Floods cause almost half of weather related fatalities.related fatalities.

Occur when so much water pours into a stream Occur when so much water pours into a stream or river that it overflows its banks and covers or river that it overflows its banks and covers the land on either side of the channelthe land on either side of the channel

Describe what happens when a flash flood Describe what happens when a flash flood occurs – why are they so dangerous?occurs – why are they so dangerous?

To stay safe during floods, move to higher To stay safe during floods, move to higher ground.ground. If your family is in a car, don’t drive across flood If your family is in a car, don’t drive across flood

waters. 60 cm of fast moving water can sweep a car waters. 60 cm of fast moving water can sweep a car away.away.

FloodsFloods How can precipitation cause flooding?How can precipitation cause flooding?

How can you stay safe during a flood?How can you stay safe during a flood?

What is the difference between a flood watch What is the difference between a flood watch and a flood warning?and a flood warning?

Name three tools that supply information used Name three tools that supply information used in forecasting floods and providing flood in forecasting floods and providing flood information (information (hint: look at the bottom of pg. hint: look at the bottom of pg. 516516))

Describe 2 weather situations in which you Describe 2 weather situations in which you would expect floods to occur.would expect floods to occur.

Predicting Weather ChangePredicting Weather Change What does a barometer measure? Describe What does a barometer measure? Describe

the weather resulting in a change in the the weather resulting in a change in the barometer.barometer. Air pressure. Falling air pressure usually indicates Air pressure. Falling air pressure usually indicates

an approaching low-pressure area, possibly bringing an approaching low-pressure area, possibly bringing rain or snowrain or snow

Describe what weather would occur if cumulus Describe what weather would occur if cumulus clouds started growing larger and taller.clouds started growing larger and taller. They would become cumulonimbus clouds, bringing They would become cumulonimbus clouds, bringing

thunderstormsthunderstorms Do meteorologists study meteors? Explain Do meteorologists study meteors? Explain

what their job is.what their job is. Where do meteorologists get their Where do meteorologists get their

information?information?

Predicting Weather ChangePredicting Weather Change Changes in technology for making predictions Changes in technology for making predictions

have occurred in 2 areas: gathering weather have occurred in 2 areas: gathering weather data and using computers to make forecasts.data and using computers to make forecasts.

Weather balloons can measure temperature, air Weather balloons can measure temperature, air pressure and humidity while weather satellites pressure and humidity while weather satellites photograph Earth’s surface, clouds, storms, ice, photograph Earth’s surface, clouds, storms, ice, snowsnow

Computers start with weather conditions Computers start with weather conditions reported from weather stations over a large reported from weather stations over a large area. They work through calculations to predict area. They work through calculations to predict the weather and adjust their reports as new the weather and adjust their reports as new data comes in.data comes in.

Predicting Weather ChangePredicting Weather Change Describe what happens with the winds and Describe what happens with the winds and

water during an El Nino event.water during an El Nino event.

What evidence do scientists use to predict an What evidence do scientists use to predict an El Nino?El Nino?

Explain the word Explain the word isobar isobar – iso…? …bar? Think – iso…? …bar? Think of other words that use “iso” and “bar”.of other words that use “iso” and “bar”.

Let’s look at a weather map in more detailLet’s look at a weather map in more detail

Predicting Weather ChangePredicting Weather Change What kinds of technology do meteorologists What kinds of technology do meteorologists

use to help predict the weather?use to help predict the weather?

Name at least 3 types of information you could Name at least 3 types of information you could get from a weather map of your area.get from a weather map of your area.

What lines on a weather map connect points What lines on a weather map connect points that have the same temperature?that have the same temperature?

If you observe that air pressure is rising, what If you observe that air pressure is rising, what kind of weather do you think is coming?kind of weather do you think is coming?