Weather &

ClimateMon-Tues

3/30-31

Take a look at climate on page

484 in your textbook

• Quiz review

• Take out your homework

• Popcorn reading

• Discussion

• Wrap up

• facts

HW: Take out your agenda• Homework: Re-read chapter

17 section 1 &3. Answer these

• What determines climate?

• How does latitude, oceans, and other

factors affect the climate of a region?

• What are causes of climate change?

SPOBGE 3/31/15

1. Why does a sea breeze

occur during the day?

2. Why does a land breeze

occur during the night?

Answers

1. When the Sun is out (day), the land gets warmer

quicker than water. Because of convection currents,

warm air rises from the land and is replaced by cooler

air from the ocean/sea. A cool breeze moves onto the

land.

2. When it is night, happens the land becomes cool

quicker than water. Because of convection currents,

warm air rises from the water and is replaced by

cooler air from the land. A cool dry breeze moves out

to the ocean.

Air Masses &

FrontsUse your handout to fill in the blanks

Air Mass

A huge body of air that has

similar temperature,

humidity (amount of moisture),

and air pressure

Types of Air

MassesMaritime Tropical

• Warm, humid air masses form over

oceans near the tropics

• In summer, brings hot humid weather

• In winter brings heavy rain or snow

• Maritime means from nearby sea or

ocean.

Types of Air Masses

cont’dMaritime Polar

• Cool, humid air masses from over the icy cold North Pacific and North Atlantic oceans

• In summer, cool humid air often brings fog, rain, & cool temperatures

Types of Air Masses

cont’dContinental Tropical

• Hot dry air masses form

only in summer over dry

areas over the southwest and

northern Mexico

Types of Air Masses

cont’dContinental Polar• Large continental polar air masses form over central &

northern Canada & Alaska

• Bring cold, dry air

• Winterclear, cold, dry air

• Summer storms may occur when continental polar air masses move south & meet maritime tropical air masses moving north

• Continental means it comes from off the land (little to no moisture)

How Air Masses

Move

In Northern Hemisphere, the

Prevailing Westerlies move

masses from West to East

- This is why most of our

weather travels from the

west to east.

Global winds (Write

this in any space provided)• Are large wind patterns that

occur in different areas on Earth

(latitudinal lines) and are caused

by the exchange of warm and

cold air that occurs between the

equator and the poles.

• This exchange creates very

large convection currents across

the globe.

• Global winds push air masses

around Earth

• CHECK OUT WHERE WE

LIVE!!!

Fronts

Area where air masses meet

and do not mix becomes a

front

- Have different temperatures

and densities. Creates

changeable weather and

storms

Types of Fronts

The kind of front that develops

depends on the characteristics

of the air masses and how they

are moving

Cold Fronts

• Cold air is dense and tends to sink (high

pressure)

• Warm air is less dense and tends to rise

(low pressure)

• When a rapidly/fast moving cold air mass

runs into a slowly moving warm air mass,

the denser cold air slides under the

lighter warm air

Cold Fronts cont’d• The warm air will cool and condense

(form clouds).

–Lots of water means heavy rain or snow

–Little water means cloudy skies

• Move quickly causing abrupt (sudden) weather changes

Warm Fronts• Moving warm air collides with slowly

moving cold air

• Warm air moves over cold air

• If warm air is humid (damp), showers & light rain fall where the air masses meet

• If warm air is dry, scattered clouds form where they meet

Warm Fronts

cont’d• Weather may last several days

(because of slow moving mass

of air)

• Weather is warm and humid

after front passes

• In winter warm fronts bring

snow

Comparing Warm

and Cold Fronts• Cold fronts move faster than warm fronts.

• The weather activity in a cold front is often violent and happens directly at the front.

• Cold fronts have sudden gusty winds high in the air creating turbulence (irregular motion/violent).

• The weather activity in a warm front generally happens before the front passes through an area. Steady rain or drizzle may fall for a long period of time.

• In a warm front the cloud formation is very low often creating situations of poor visibility.

Stationary Fronts

• Neither the cold or warm air

mass has enough force to move

the other

• Where masses meet, clouds

form to make rain, snow, or fog

• Stationary fronts can cause

many days of dreary weather.

• https://www.youtube.com/wa

tch?v=tkK4_F0VKhM

Occluded (cut off) Fronts• Warm air mass caught between two cold

air masses

• The denser cool air masses move underneath the warm air mass and is pushed upward

• Ground temperature cools

• Weather may turn cloudy and rainy or snowy

• http://www.phschool.com/atschool/phsciexp/active_art/weather_fronts/

Cyclones & Anticyclones (not a tornado)

Cyclones

• Swirling center of low

air pressure

• Cyclones and decreasing

air pressure are

associated with storms

and precipitation

Anticyclones• High pressure

centers of dry air

(wind spiral

outward from

center)

• Causes dry, clear

weather

Anticyclone Cyclone

• high pressure= cold/sinking air

• low pressure = warm/rising air

• The slightly inward moving air in low pressure causes air to come

together and become heated by the surface; the air is forced upward,

leading to condensation and precipitation. The opposite occurs with

high pressure. Air is moving away from the high pressure/cold center .

As air from the surface is heated and rises, air from above must sink to

take its place

What Causes

Climate?

Climate

Average, year-after-year

conditions of temperature,

precipitation, winds, and

clouds in an area

Factors of Climate

• Temperature (tilt of Earth)

• Precipitation (amount of

moisture in clouds)

Factors of

Temperature• Latitude

• Altitude (distance upward)

• Distance from large bodies of water (sea and land breeze)

• Ocean currents

Factors of

Precipitation• Prevailing winds

• Presences of mountains

(can cause area behind

mountain to become dry

and warm)

Seasons

Seasons are the result of the

tilt of Earth’s axis

Wednesday-

Friday• BrainPop- Tornado vs.

Hurricanes

• Read textbook

• Begin Storm brochure; use

textbook, brainpop, and

articles to assist you.

SEVERE WEATHER

- A thunderstorm is a weather event where there is heavy rain,

lightning, thunder roars, and possible hail.

How do they form?

-They occur in warm moist air masses and along fronts.

-The air is forced upward where it is __________, and

condensation occurs forming _________________clouds.

-Then __________________ happens in the form of rain or

hail. The rain cooled air sinks and strong updrafts of warmer

air causes strong winds.

cooled

cumulonimbus

precipitation

What is a thunderstorm?

Can thunderstorms cause damage?

• YES!

• How?

• By flooding

• Hail damage

• Wind damage

• Lightning strikes

What is lightning?Lightning is a bright flash of electricity produced by a

thunderstorm. All thunderstorms produce lightning and are very dangerous. If you hear the sound of thunder, then you are in danger from lightning. Lightning kills and injures more

people each year than hurricanes or tornadoes; between 75 to 100 people.

What causes lightning?Lightning is an electric current. In a thundercloud, many small bits of ice

(frozen raindrops) bump into each other as they move around in the air. All the collisions create an electric charge. Once the cloud fills, with electrical charges, the positive charges form at the top of the cloud and the negative

charges form at the bottom of the cloud. Since opposites attract, this causes a positive charge to build up on the ground beneath the cloud. The

grounds electrical charge concentrates around anything that sticks up, such as mountains, people, or single trees. The charge coming up from

these points eventually connects with a charge reaching down from the clouds and - zap - lightning strikes!

Lightning can also form within or between clouds, not just

from the cloud to the groundLightning also forms within and between clouds.

Thunder is caused by lightning. When a lightning bolt travels from the cloud to the ground it actually opens up a little hole in the air, called a channel. The lightning heats up the air and

causes it to expand. Once the lightning is gone the air collapses back due to quick cooling, and creates a sound wave that we hear as thunder. The reason we see lightning before we hear thunder is because light travels faster than sound!

Which do you think is hotter, a bolt of lightning, or the surface of the sun?

Lightning- it is 30,000 degrees Celsius. That’s 5 times hotter than the sun!!

What causes thunder ?

How do tornadoes form?

When thunderstorms develop, a change in wind direction and an increase in wind speed with increasing height creates an

invisible, horizontal spinning effect in the lower atmosphere; this is wind shear. Rising air from the updraft of a

thunderstorm tilts the rotating air from horizontal to vertical. An area of rotation, 2-6 miles wide, now extends through much of the storm. Most strong and violent tornadoes form within

this area of strong rotation.

Know the Lingo TORNADO WATCH - Tornadoes are possible in your area. Stay tuned to the radio or

television news.

TORNADO WARNING - A tornado is either on the ground or has been detected by Doppler radar. Seek shelter immediately!

Measuring Tornadoes

The Fujita Scale

F0gale tornado40-72 mph

Some damage to chimneys; breaks branches off trees; pushes over shallow-rooted trees; damages sign boards.

F1moderate tornado73-112 mph

Lower limit is the beginning of hurricane-force winds. Peels surface off roofs; mobile homes pushed over; moving autos pushed off roads.

F2significant tornado113-157 mph

Roofs torn off frame houses; mobile homes demolished; boxcars pushed over, large trees snapped or uprooted; light-object missiles generated.

F3severe tornado158-206 mph

Severe damage. Roofs and some walls torn off well-constructed homes; trains overturned; most trees in forest uprooted; heavy cars lifted off the ground and thrown.

F4devastating tornado207-260 mph

Well-constructed homes leveled; structures with weak foundations blown off some distance; cars thrown and large missiles generated.

F5incredible tornado261-318 mph

Phenomenal damage. Strong frame homes disintegrate or lifted off foundations and carried considerable distance; trees debarked.

The geography of the central part of the United States, known as the Great Plains, is suited to bring all of the

ingredients together to forms tornadoes. This includes Texas, Kansas, and Oklahoma. More than 500 tornadoes typically

occur in this area every year and is why it is commonly known as "Tornado Alley".

Where are tornadoes most likely to occur?

What is a hurricane?

A hurricane is a huge storm! It can be up to 600 miles

across and have strong winds spiraling inward and

upward at speeds of 75 to 200 mph. Hurricanes usually

lasts for over a week, moving 10-20 mph over the open

ocean. Hurricanes gather heat and energy through

contact with warm ocean waters. Evaporation from the

seawater increases their power. Hurricanes rotate in a

counter-clockwise direction around an "eye." The center

of the storm or "eye" is the calmest part. It has only light

winds and fair weather. When they come onto land, the

heavy rain, strong winds and large waves can damage

buildings, trees and cars. Similar storms are called

typhoons in the Pacific Ocean and cyclones in the Indian

Ocean.

How do hurricanes form?Hurricanes form over warm ocean water of 80°F or warmer. The atmosphere must cool off very quickly the higher you go. The wind must be blowing in the same direction and at the same speed to force air upward from the ocean surface. Winds flow outward above the storm allowing the air below to rise. Hurricanes typically form between 5 to 15 degrees latitude north and south of the equator. The Coriolis effect is needed to create the spin in the hurricane.

Saffir-Simpson Hurricane Scale

Category Winds (MPH)Storm Surge

(Feet)Damage

1 74-95 4'-5' Minimal2 96-110 6'-8' Moderate3 111-130 9'-12' Extensive4 131-155 13'-18' Extreme

5 >155 >18' Catastrophic

Can Hurricanes cause damage?

• Absolutely!

• Storm surges usually cause the most damage and death

• Winds can destroy homes and uproot trees

• Extensive rain can also cause major flooding

Shallow-Water Coastline

Deep-Water Coastline

What is a storm surge?

Know the LingoTROPICAL STORM WATCH - Tropical Storm conditions with sustained

winds from 39 -74 mph are possible in your area within the next 36 hours.

TROPICAL STORM WARNING - Tropical Storm conditions are expected in your area within the next 24 hours.

HURRICANE WATCH - Hurricane conditions with sustained winds of 74 mph or greater are possible in your area within the next 36 hours.

This WATCH should trigger your family's disaster plan, and protective measures should be initiated. Especially, those actions that require

extra time such as securing a boat and leaving a barrier island.HURRICANE WARNING - Hurricane conditions are expected in your

area within 24 hours. Once this WARNING has been issued, your family should be in the process of completing protective actions and deciding

the safest location to be during the storm