Transcript Weather/Natural Disasters

WEATHER
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 730 miles from earth, is
40 degrees, and
contains the ozone
layer and fighter
planes.
The mesosphere is at 3050 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 spread
from 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
FYI
The rainiest spot on
earth is Mt. Waiaheale,
Hawaii. It gets about
471 inches of rain a year.
FYI
When 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 off
accumulation
infiltration
transpiration
run off
water that has fallen as rain
and has stayed on the
surface of the earth. It
moves from higher to
lower elevations as "runoff“.
accumulation
water collected in lakes,
rivers, streams, oceans,
etc. that will evaporate
into water vapor
Infiltration
the 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)
Transpiration
water given off as
microscopic water
vapor from the bottom
of plant leaves
FYI
The 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.
FYI
A flash of lightning
can sometimes be
over 5 miles long.
FYI
Lightning temperatures can
reach over 50,000 degrees
F. THAT’S 5 TIMES
HOTTER THAN THE
SUN’S SURFACE.
FYI
More 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.
LIGHTNING
STEPS
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
top of cloud: positive charge
bottom of cloud: negative charge
When there are
more negative than
positive charges in
the cloud, the extra
negative charges go
toward the ground
Lightning occurs where
the positive and negative
charges meet
Things on the
ground have a
positive charge.
Positive
charges are sent
into the air.
There are three types
of lightning:
cloud-to-air
cloud-to-cloud
cloud-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.
FYI
Thunder 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 lowpressure 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 hurricanearea where there
is 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 funnelshaped 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.
SAND
STORMS
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 from
Egypt 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 2040 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.
Human
Causes
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.
Natural
Causes
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.
The
Earth’s
Tilt
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.
FYI
The driest place on earth
is Arica, Chile. Its gets
only 0.3 inches of rain a
year.
FYI
The hottest place in the
world is Dallol, Ethiopia
where the average
temperature year round is
between 95 and 100
degrees F.
FYI
The “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.
Greenhouse
Effect
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 manmade 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.