Name _________________________________ Period _________________ Date _______________________

Unit 12: The Atmosphere & Weather (Part 2)Air Pressure & Wind

What is Air Pressure?

• Air (Atmospheric) Pressure: the _____________ exerted by the _____________________ above it

• As you move through the atmosphere you will experience a gradual change in pressure

• Pressure slowly _____________ the farther you go up

Measuring Air Pressure:

• ______________________ – air pressure pushes a column of mercury upward in a tube. The __________ the air pressure, the __________ the mercury rises

• _______________ Barometer – walls bend in and out based on air pressure. The ____________ of the chamber causes a ______ to move which indicates a change in pressure.

Why does air pressure matter?

Why do places have different air pressures?

• _____________________ creates air pressure differences

• __________ is created because air flows from an area of _________ pressure to an area of _________ pressure

• Areas of High pressure are characterized by:

• ______________________

• Winds blowing away in _______________ motion (in ______________ Hemisphere)

• Leads to “__________” weather

• High Pressure = _______________

Areas of Low pressure are characterized by:

• ____________________

• This leads to ___________________________

• Winds rotate in a _________________________ motion (in ___ Hemisphere)

• Low Pressure = __________

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Factors of Wind

What makes some places windier than others?

• Two factors:

1) ____________________________

2) ____________________________

1) Pressure Differences

• Wind is caused by differences in air pressure.

• The ______________ the difference the ________________ the ________________.

• __________ are connected lines of _______ pressure

• The spacing between each isobar indicates pressure change

• The _________ the lines of an isobar are together, the steeper the pressure gradient (changes in pressure)

• Close Isobars= _______________

• Widely Spaced Isobars= _____________

2) Coriolis Effect

• The ____________ of the Earth deflects wind direction

• In the Northern Hemisphere to the ________

• In the Southern Hemisphere to the ________

• The ___________ you move the ______________ the effect

Low Pressure

L

Without Coriolis Effect With Coriolis Effect2

High Pressure

HWithout Coriolis effect With Coriolis Effect

Does the Coriolis Effect have an impact on toilet water in each hemisphere?

Global Winds

• Winds caused by uneven ____________ of Earth’s atmosphere.

• Equator gets more direct ______________

• Equatorial air expands, _______ and flows ________________

• Polar air is more __________ so it flows toward the equator

• Non-rotating Earth, ________ (North & South)

• Due to the Earth’s rotation, instead of two cells you have _______.

• Why do we have six?

• High pressure around 30° and low pressure around 60°

• ___________________

• ___________________

• Three winds in each hemisphere

• Trade winds – blow from the ______

• Westerlies – blow from the _______

• Polar Easterlies – blow from the _______

Jet Stream

• _____________ – a fast flowing current of air located between 5-7 miles above the surface of the Earth

• In the northern hemisphere they flow from _______________

• _______ Jet Stream is found at 60° and the _______________ jet stream is found at 30°

• Can move at speeds of more than 275 mph

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Wind

• Wind is the movement of air from places of _______ pressure to places of ______ pressure

• Wind moves in large masses called ________________

• Air masses also move from areas of ______ pressure to areas of _______ pressure

• These air masses retain the characteristics of ____________________

Types of Air Masses

• Air masses can be described in two ways

1) ______________

• Continental (_____ air) vs. Maritime (______ air)

• If the air mass forms over land or water determines if it carries a lot of moisture or not

2) __________________

• Tropical (_________ air) vs. Polar (______ air) vs. Arctic (___________ air)

• The temperature of the air mass depends on if it formed closer to the equator or closer to the poles

Knowing moisture and temperature, what would the characteristics be of…

• Continental Polar (cP)?

• Maritime Tropical (mT)?

• Continental Arctic (cA)?

Fronts

• _________ – the boundary between two different _________________

• Along a front, _______________________________________

• 4 types of fronts

• ___________

• ___________

• ______________

• _______________

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Warm Front

A warm front occurs when ______________________________ _______ an area covered by cooler air.

• Takes a ______________ for warm air to displace colder air

• Marked by long and steady rain

• __________________________ are symbols for warm front

Cold Front

• A cold front forms when _______________________ moves into an area occupied by warm air

• Compared to speed of warm front, cold fronts move _________________

• Marked by ____________________________________ for a short period of time

• ______________________ are symbols for cold front

Stationary Front

• If fronts are _______________________________ each other

• Mild precipitation can occur on a stationary front

• ___________________ on one side, ____________________ on other

Occluded Front

• Cold fronts move _______________ than warm fronts

• When an active cold front _______________ a warm front, an occluded front forms

• This will force the warm front up into the air, which will lead to _________________________

• Usually marked by ______________ semi-circle and triangles in _________________

Thunderstorms

Thunderstorms- a violent weather event accompanied by _________________________________________

• There are ~ ___________ thunderstorms per day worldwide

• Thunderstorms form when __________________ air rises into (above) _________ air in an unstable environment

• There are two kinds of thunderstorms: Cold front and Warm air

Cold Front Thunderstorm

• Warm air is pushed ______________ cold air

• Strong and last for several hours.

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• Mostly in _____________________.

• Can also have tornadoes and hail.

Warm Air Thunderstorm

• Caused by ______________________ of Earth’s surface

• Less violent and usually last less than hour

• Usually occur in __________

Thunderstorm Stages

1) _________________: strong ___________ blow warm, moist, air higher until the vapor condenses, forming a cumulus clouds

2) _________: violently rising, warm air forms ________________ clouds

Updrafts continue and ______________ begin as rain starts to fall

Thunder and lightning begin

3) ________________: strong downdrafts ________ warm, moist air currents from rising.

Water vapor supply suddenly __________ so the cell dies down

If the storm passes over new areas of warm water then new cells can begin again

Lightning

• No one actually knows exactly what causes lighting but…

What causes lightning?

• Simple Answer: The ________________ of ___________________.

What causes lightning? (More detail)

• ___________________ particles move quickly through a cumulonimbus cloud by updrafts and downdrafts

• The particles interact and exchange energy

• ________________ are sheared off of ascending particles and they ______________ on the _________________ particles

• _______________ charges collect near the _____________

• _______________ charges near the _______.

• The negative bottom of the cloud induces a collection of _____________ charge on the _____________________

• A negatively charged _______________________ comes from the cloud down

• The object that is about to be stuck sends a positive “_______________” up to meet the leader6

• When the two paths __________, electricity moves down the path to the ground and a __________________ is sent back into the sky and causes the _________________ of the lightning

• It all happens so quickly so we can’t really see the different parts without an awesome camera!

Thunder

• As electricity flows through the air it raises the temperature to ______________

• This rapidly ________________ and _____________________ the surrounding air which produces a _______________

• The shock wave produces ________________________ that we hear as a crack of thunder

• We hear thunder rumble as the initial sound waves _____________________ of other things and because they begin at ______________________________ away from us

• Light travels _________ than sound so we see lightning before we hear any sound

• Thunder is the _________ of lightning!!

Tornadoes

A rapidly spinning column of air that has _________ winds, _______ pressure and touches the ground.

• The center of a tornado is characterized by its ________________

• Often associated with very strong thunderstorms called _______________

• Scientists don’t know exactly what causes tornados but they know that these conditions are necessary:

• ____________________________ – unusually warm, wet lower air and colder upper air

• ___________________ – wind speed increasing and direction changing with altitude

• Ex. southerly wind of 15 mph at the surface, changing to a southwesterly or westerly wind of 50 mph at 5,000 feet altitude

How to form a tornado:

1. _________________ rolling winds are created

2. Rolling winds hit an _______________ and start to tilt upward.

3. Rotating winds now in _____________

4. Rotating winds can touch down and form tornadoes

Tornado Alley

Tornado Alley occupies a unique geographic position where ________________ air from the Gulf of Mexico, _______________ air from Arizona and New Mexico, and _____________ air from Canada meet

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Tornado Intensity: EF0 – EF5

• Measured on the Enhanced __________ Tornado Intensity Scale

• Measures how much ______________ is done by the tornado and wind speed

Tornado Warning System

Watch

• Conditions are _____________ to the development of tornadoes in and close to the watch area. • _________ area• Can last 3-5 hours

Warning

• A tornado has been ___________ by spotters or indicated on radar and is occurring or imminent in the warning area.

• __________ area

• Can last 30 min – 1 hour

Hurricanes

• Whirling tropical cyclones that produce sustained winds of at least __________ or 119 kph.

• Center of _______ pressure

• Rotate ____________________ in the N. Hemisphere

• Hurricanes go by different names in other parts of the world, these severe tropical storms can be called:

• In the Pacific they are called ____________

• In the Indian Ocean they are called __________

Hurricane Anatomy

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Parts of a Hurricane

• ______ – center of the hurricane

• ___________ and warmest part of the storm.

• _____________ – Thick clouds surrounding the eye with the most ____________ winds of the hurricane

Stages of a Hurricane

• Tropical ______________ - is the first stage of consisting of a mass of thunderstorms that have only a slight wind circulation.

• Tropical _____________ - whirling area of low pressure and storm activity with sustained winds _____ mph or less.

• Tropical ____________ - sustained winds ______ _____ mph. This is the stage when the storm is given a name.

• Hurricane – winds at or over ______ mph

Storm Surge

• ________________________ from hurricanes comes from the storm surge.

• Storm Surge - a combination of high tide and water that is pushed onshore by the _________________ of a hurricane; can produce surges 1-5.4+ meters.

• Most deaths from hurricanes are by _____________ due to the storm surge.

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Hurricane Classification

Hurricanes are classified according to intensity using the Saffir-Simpson scale (Category 1-5)

• Hurricane Watch: issued several days before landfall

• Hurricane Warning: issued 24 hours before landfall

Naming & Forecasting Hurricanes

• 1953: names were ___________ and in _______ order

• 1979: began alternating ______________________ names

• The list of names was created by the World Meteorological Society and names are recycled every _____________

• EXCEPTION: If a hurricane was particularly destructive or noteworthy, the name will be ___________ and replaced on the list with another name beginning with the same letter

Hurricane season in the South East US is _________________________

• The interaction between ocean water temperatures and warm air masses contributes to the formation of hurricanes during the late summer

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