WEATHERWEATHER

71% of the earth is water.

Water Dispersal on Earth

The mass of air that surrounds the earth is the

atmosphere.

Water is found in the atmosphere in the form

of rain, snow, hail, sleet, water vapor and the

water droplets that make up clouds.

All these gases are held in the

atmosphere by the earth’s gravitational

pull.

There are five layers to the

earth’s atmosphere

•troposphere•stratosphere•mesosphere•thermosphere•exosphere

The troposphere is between 0-7 miles from earth’s surface and contains

clouds, weather, water and dust particles, flying

animals, and commercial air traffic.

The stratosphere is 7-30 miles from earth, is

40 degrees, and contains the ozone layer and fighter

planes.

The mesosphere is at 30-50 miles. It is the coldest part of the atmosphere (at

–90 degrees) and only large helium balloons fly

there.

The thermosphere is located 50-300 miles from

earth and is the hottest layer (930-3,000 degrees).

Satellites, Sputnik, and the X-15 can go there.

The exosphere is any area in space over 300 miles from

earth. There are no atmospheric gases from earth in this layer.The shuttle and

other space ship can go there.

About halfway through the thermosphere at 180 miles, the atmosphere merges with the thin

gases of interplanetary space.

Weather is the condition of the lowest layer of the atmosphere at a particular time and

place.

We experience weather in

precipitation, wind, temperature, and

humidity.

The Coriolis effect is the way the winds

swirl around the earth because of its

rotation.

This circulation of air is mainly responsible

for the weather conditions around the

world.

Nuclear fallout from the Chernobyl nuclear

incident spread throughout Europe

You can see how the volcanic ash spreadfrom Alaska to Canada in a

three day period.

The consistent movement of air in a

specific direction over an area is called a

jetstream.

There are two jetstreams that

cover the United States.

This causes the air in the United States to

consistently move in a certain direction.

One jetstream brings cold air from the north.

The other brings warmer and moister air

from the south.

These bands of moving air run from west to

east, basically splitting the United States in

half.

A cloud is a mass of billions of tiny

droplets of waters or ice crystals floating

above earth.

Clouds form when warm, moist air meets cold air.

It is only when water droplets repeatedly collide and fuse together into large droplets,

that they finally become heavy enough to fall as rain.

3 basic types of clouds

•cumulus

•stratus

•cirrus

CUMULUS

STRATUS

CIRRUS

STRATOCUMULUS

Some unusual clouds

supercell: thunderstorms and tornadoes

Contrails are white cloud-like shapes in the

sky made by aircraft when moisture from

burning fuel meets cold air.

air traffic around world

FYIThe rainiest spot on

earth is Mt. Waiaheale, Hawaii. It gets about

471 inches of rain a year.

FYIWhen a city the size of Chicago gets 1 inch of

rain, over 4 billion gallons of water fall.

Precipitation is any kind of water

or ice that falls from the clouds.

The water on earth is continually being changed from one form to another.

This change in the state of matter of water is called the

water cycle.

There are 7 steps to the water cycle.

Water in lakes and oceans is heated by the sun’s energy and rises into the air (evaporation)

In evaporation there is a change of water from a

liquid to a gas.

The water rises high enough to freeze and form a cloud

(condensation)

In condensation there is a change of water from a

gas to a solid.

The water falls from the cloud as rain,

sleet, hail, or snow (precipitation)

When the water returns to earth, four things can happen:

run offaccumulation

infiltrationtranspiration

run offwater that has fallen as rain

and has stayed on the surface of the earth. It

moves from higher to lower elevations as "runoff“.

accumulationwater collected in lakes, rivers, streams, oceans, etc. that will evaporate

into water vapor

Infiltrationthe flow of water from the ground surface into the ground where it

becomes soil moisture or collects as groundwater. (water stored beneath

the earth's surface between saturated soil and rock that supplies wells

and springs)

Transpirationwater given off as

microscopic water vapor from the bottom of

plant leaves

FYIThe largest hailstone on

record weighed 1.7 pounds and measured 17.5 inches in circumference. It fell in

1970 in Coffeyville, Kansas.

FYI In June 1932, a

hailstorm in China killed 200 people and

injured thousands more.

In areas of high pollution, dirt

particles contain chemicals.

When they attach to the water droplets in the cloud and fall to

earth, they are called acid rain.

There are over 100 lightning

strikes on earth every second.

In North America alone, about 400 people a year are struck by lightning,

a quarter of them fatally.

Lightning is caused by electrical currents that pass between a

cloud and the ground.

FYIA flash of lightning can sometimes be over 5 miles long.

FYILightning temperatures can reach over 50,000 degrees

F. THAT’S 5 TIMES HOTTER THAN THE

SUN’S SURFACE.

FYIMore people are killed by lightning each year

than by hurricanes, blizzards, or tornadoes.

typical marks from a lightning strike

Forest fires are frequently caused by lightning strikes.

When lightning is not accompanied by rain, forest

fires will quickly spread over a large area.

LIGHTNINGLIGHTNING

STEPSSTEPS

1. clouds have a negative charge

2. ground has a positive charge

3. clouds send their negative charge down

4. ground sends its positive charge up

5. lightning occurs where the two charges meet

Things on the ground have a

positive charge. Positive

charges are sent into the air.

top of cloud: positive chargebottom of cloud: negative charge

When there aremore negative thanpositive charges inthe cloud, the extranegative charges go toward the ground

Lightning occurs wherethe positive and negative

charges meet

There are three types of lightning:cloud-to-air

cloud-to-cloudcloud-to-ground

cloud-to-air

least powerful

caused by too much positive charge in air

surrounding cloud

CLOUD-TO-AIR LIGHTNING

cloud-to-cloud

most common type

travels within a cloud or from cloud to cloud

higher clouds, so too far away to hear thunder

CLOUD TO CLOUD LIGHTNING

cloud-to-ground

negative charge in base travels to

positive charge from ground

CLOUD-TO-GROUND LIGHTNING

Lightning comes in many

different colors.

lightning colors• red means rain in the cloud• blue means hail in the cloud• yellow is caused by dust • white means low humidity

(most forest fires are started by white lightning)

Thunder is created because some of the tremendous

energy of lightning flashes is turned into heat and then

into sound waves.

FYIThunder is heard an

average of 242 days a year in Kamal, Uganda.

FYI

The Empire State Building in New York City is hit by lightning about 42 times a year.

A hurricane is a storm in which strong winds whirl around a low-

pressure center.

A hurricane is made of hundreds of large thunderstorms that spiral around each

other.

The winds blow at speeds of 100 miles per hour or greater, sometimes reaching 200 miles per hour.

They occur in a narrow band

between 0 to 30 degrees on either

side of the Equator.

The reason for this that they require

ocean temperatures of at least 80 degrees to

form.

spinning winds

eye of hurricane-area where thereis no rain or winds

Hurricane-like storms in the Pacific are called typhoons.

A tornado, or twister, is a

destructive storm with whirling

winds.

The winds make their way to earth as a spinning funnel-

shaped cloud.

Tornados can occur individually or in

large groups, as large as 100 to 150.

That conditions that create a tornado

involve warm, humid air meeting dry air

and cool, humid air.

The Fujita Tornado Scale is a scientific

classification system to categorize the strength of a tornado. It ranges

from 1-5.

Most tornadoes only rate 1 on the Fujita scale meaning there is very little damage. Only about 1% of all tornadoes are rated 4-5 on the

scale, meaning that they are extremely destructive.

The Beaufort Wind Scale

classifies a wind’s strength.

A water spout is a tornado like structure that develops over the

water.

Unlike a tornado, a water spout forms from the

water to the sky.

SANDSTORMS

Sandstorms occur in desert areas like the Middle East and the Southwestern parts of the

U.S. (like Arizona) and are caused by strong winds

blowing over loose soil or sand.

Dust storm traveling fromEgypt to Saudi Arabia

Poor visibility for driving and respiratory

problems can cause deaths.

Climate is the average weather in an area over a long

period of time.

It is classified based on two factors: amount of

precipitation and normal yearly temperatures.

Climate is categorized into

five systems.

Polar climate has permanent snow or ice

and only light precipitation. The

warmest month is 50 degrees.

Humid and cold climates have hot summers and

cold winters with a low of 27 degrees and an average rainfall less than 20 inches

a year.

Warm and rainy climates have mild winters with the coldest month between 27

and 64 degrees. The average yearly rainfall is between 20-

40 inches.

Tropical rain climates average no less than 64 degrees at any time. The

average rainfall in a year is 72-180 inches, with 6-15

inches in the rainy season..

Dry climates are areas that average less than 10 inches of rainfall a year.

The causes of climate change can be divided

into two categories - those that are due to natural

causes and those that are created by man.

 

HumanCauses

Land that was covered with

vegetation has been cleared to make way

for houses.

Natural resources are being used

extensively for construction,

industries, transport, and consumption.

Consumerism: humans are daily creating

mountains of waste. Recycling could help greatly reduce the

amount of garbage that is collected each year.

Population has increased to an

incredible extent.

All this has contributed to a rise in greenhouse gases in the atmosphere.

Greenhouse gases and their

sources

Deforestation, land clearing, agriculture, and other activities have all

led to a rise in the emission of carbon

dioxide.

Methane is another important

greenhouse gas in the atmosphere.

About ¼ of all methane emissions are said to come from domesticated animals such as dairy cows, goats, pigs, buffaloes, camels,

horses, and sheep.

Methane is also released from rice or paddy

fields.

Methane is also emitted from

landfills and other waste dumps.

NaturalNaturalCausesCauses

There are a number of natural factors responsible for

climate change.

Some of the more prominent ones are continental drift, volcanoes, ocean currents, the earth's tilt, and comets

and meteorites.

Continental Drift

Continental drift had an impact on the climate because it

changed the physical features of the landmass, their geographic

position and the position of water bodies.

Volcanoes

When a volcano erupts it throws out large volumes of sulphur dioxide (SO2), water

vapor, dust, and ash into the atmosphere.

The large volumes of gases and ash can influence climatic patterns for years.

The gases and dust particles partially

block the incoming rays of the sun,

leading to cooling.

TheEarth’sTilt

Changes in the tilt of the earth can affect the severity

of the seasons - more tilt means warmer summers and colder winters; less tilt means cooler summers and milder

winters.

Elevation is the distance above

sea level.

As you go higher up a mountain, the air pressure

decreases and the gas molecules spread farther

and farther apart and hold less heat, so it becomes

colder.

Latitude determines the amount of solar energy received by

that region.

Regions close to the equator receive direct

rays of the sun and therefore receive more of

the sun’s heat and are warmer.

At the areas closer to the poles, the sun’s rays are at an angle so these areas receive less sun’s

heat and are cooler.

Water, like air, moves around the earth as warm or cold winds and

currents.

It moves in a cycle from ocean, to air, to land, and back to

oceans.

Water in the ocean travels in

paths called currents.

Currents can either be warm

or cold.

The temperature of the water affects the temperature of the

air above it.

If the water is cold, it cools the

air above it.

If it is warm, it heats up the air

above it.

Ocean currents traveling away

from the equator are warm.

Currents flowing toward the equator are

colder.

These cooled air masses then flow

over the regions in their path.

Much of the heat that escapes from

the oceans is in the form of water vapor.

Water vapor contributes to the formation of

clouds, which shade the surface and have a net

cooling effect.

It is important to us that the oceans stay

healthy.

They drive our climate and weather.

Oceans provide a livelihood for many millions of people worldwide through fishing,

energy and mineral resources, shipping, and

leisure activities

Oceans pose threats through floods, tsunamis, storms, sea

level change and coastal erosion. More than half the

world’s population lives near the sea.

Most waste eventually ends up in the oceans, with the

result that marine pollution is a global problem - every part of every ocean is now

affected.

The amount of precipitation in a

region is affected by mountain ranges in

that area.

Mountains cause air to

rise.

Rising air becomes less dense allowing the condensation of water. Precipitation

occurs.

Winds can greatly affect the amount of

precipitation an area receives depending on the amount of moisture

they are carrying.

These winds can move air masses from the

ocean onto a continent bringing moisture onto

the continent.

Or winds may move air masses from continent to the ocean, moving

drier air from the continent.

These winds affect the climate

of an area.

FYIThe driest place on earth is Arica, Chile. Its gets only 0.3 inches of rain a

year.

FYIThe hottest place in the

world is Dallol, Ethiopia where the average

temperature year round is between 95 and 100

degrees F.

FYIThe “Pole of Cold” in

Antarctica is the coldest place on earth. The average temperature is –72 degrees F and down to –130 degrees F

in July.

GreenhouseEffect

The greenhouse effect occurs when carbon

dioxide levels in the air build up and hold heat in the earth’s atmosphere.

It causes a reduction in the ozone layer and global warming.

Scientists measure the temperature at many

different locations several times each day to

determine how much the earth’s temperature is

increasing.

We are currently in one of the warmest

periods in our earth’s history.

Another way we are altering the weather in a dangerous

way is by pollution. Chemical pollutants in the air create

acid rain and smog.

Smog is a kind of man-made weather, a

combination of smoke and fog that is darker and heavier than normal fog.

Chemicals in the atmosphere open holes in the ozone layer

and allow harmful rays to reach earth’s surface. This increase can heat the planet and increase the risk of skin

cancer.