2. What is wind?
Wind is the horizontal
movement of air from an area
of high pressure to lower
3. What Causes Wind?
Wind is the movement of air caused by
differences in air pressure. The uneven
heating of the earth produces these
pressure belts, which cause winds; the
air rises and sinks (convection
currents). When this happens at the
poles of the earth, global winds occur.
These winds move all over the world.
6. DIFFERENCES IN TEMPERATURE
1. Warm air rises.
Warming air make the
molecules move faster
and spread out.
This makes the air less
Less dense air is light and
7. DIFFERENCES IN TEMPERATURE
2. Cold air sinks.
Cooling air makes the
molecules move slower
and group together.
This makes the air more
More dense air will sink.
8. DIFFERENCES IN PRESSURE
1. Rising air creates Low pressure.
If air is lifted up, that means there is Less air
pushing down on Earth.
2. Sinking air creates High pressure.
If air is sinking, then air is pushing down on the
surface of Earth with a High amount of pressure.
9. The Creation of Wind
1. Differences in temperature cause air to rise and sink
all over Earth’s surface.
2. Rising and sinking air creates high and low pressure.
3. The atmosphere does NOT like UNBALANCED
IT TRIES TO EQUAL OUT PRESSURE BY MOVING AIR
FROM HIGH TO LOW PRESSURE.
10. Winds are created by …
1. Heating the air, decreases pressure (warm air rises
creating a low pressure area).
2. Cool air rushes in to replace the warm air (cooler,
denser, air produces high pressure).
3. As air goes from high pressure to low pressure,
4. Wind is a horizontal movement of air.
5.There are 2 types of winds: local & global.
11. Global Winds
Global winds are patterns
of wind that happen all
over the world. They are
created by the spin of the
earth and the difference
13. Polar Easterlies
These winds blow close to the
north and south poles. They
blow away from the poles and
curve east to west. These winds
are cold, dry winds.
14. Trade Winds
Trade winds are winds that
circle near the equator.
Trade winds have been used
by ships sailing the ocean for
centuries. They help ship
captains know which
direction they are going.
15. Local Winds
Local winds in one particular area. Types of local
16. During the day, the sun heats the ocean and the land. The land heats up
much quicker than the large ocean does. This causes the air above the
land to heat up and rise. The cool air from the water moves toward the
land to replace the rising warm air. When the air moves from the sea to
the land, this is called a sea breeze.
17. At night, a land breeze occurs near the ocean. The air above the land cools
down fast, while the air above water stays warm. The cool air from the land
sinks and moves toward the ocean to replace the rising warm air. When the
air blows from the land out to the sea, this is called a land breeze.
18. During the day, the sun heats the valley air quickly. The warm
air rises and moves up the mountain. This creates a valley
19. Mountain Breeze
At night, the mountain air cools faster than the valley. The
cool air sinks down the mountain causing the wind to move
in the opposite direction. This creates a mountain breeze.
22. •Occur in many parts of the world
•Found most frequently in the United States east of the Rocky
•Most frequent during the spring and summer months.
•An average of 800 tornadoes are reported nationwide each year
•80 deaths and over 1,500 injuries average per year.
•Capable of tremendous destruction with wind speeds of 250 mph
•Damage paths can be in excess of one mile wide and 50 miles
23. • Some tornadoes may form
during the early stages of
• Occasionally, two or more
tornadoes may occur at the
• Tornadoes may appear nearly
transparent until dust and debris
are picked up.
• Waterspouts are weak tornadoes that
form over warm water.
25. A lower cloud base in the center of the
photograph identifies an area of rotation
known as a rotating wall cloud. This area is
often nearly rain-free. Note rain in the
Moments later a strong tornado develops
this area. Softball-size hail and damaging
"straight-line" winds can occur with this
Look out for:
•Dark, often greenish sky
•Loud roar; similar to a
26. • Tornadoes hide in many ways -- under cover of
darkness, heavy rain, landscape.
• They usually develop in areas in which a severe
thunderstorm watch or warning is in effect. Remain alert
to signs of an approaching tornado and seek shelter if
threatening conditions exist
27. • In a home or building, move to a pre-
designated shelter, such as a basement.
• Stay away from windows
• If an underground shelter is not available, move to
an interior room or hallway on the lowest floor and
get under a sturdy piece of furniture.
Interior bathroom was all that was left standing of this house:
• Mobile homes, even if tied down, offer little
protection from tornadoes and should be
28. • Get out of automobiles.
• Do not try to outrun a tornado in
your car; instead, leave it
29. • Go to an inside hallway at the lowest level (central 1st floor hallway).
• Stay inside
• 1st floor aisle side cubicles under work surface
• Rooms (restrooms, etc. adjoining 1st floor aisle
• Avoid places with wide-span roofs areas
• Move away from exterior walls and windows
• Get under a piece of sturdy furniture such as a cubicle work surface or heavy
table or desk and hold on to it. (Several of the people that survived the Jarrell
tornado lived because they had gotten into a bathtub).
• Use arms to protect head and neck.
31. What is a Hurricane?
A hurricane is a large, spinning wind
system that develops over warm seas
near the equator.
Hurricanes are technically tropical
They are characterized by rotating winds
that have the speed of about 75 mph
32. The tropics mostly have the most extreme
The air heated by the sun rises swiftly which
creates areas of very low pressure, the warm
air rises then it becomes loaded with moisture.
It creates into a massive thunder cloud.
It can be formed into a huge circle that can be
up to 1,200 miles across.
33. A Hurricane Begins
Hurricanes usually begin in the steamy, late
summer in the tropics, when the seas are the
For the hurricanes to develop, the sea surface
temperature has to be at least 78 degrees
When the warm air rises from the seas and
condenses into clouds.
34. The result of this mixture of heat and moisture
is often a collection of thunderstorms, from
which a tropical storm can develop.
During the hurricane season, the coriolis effect
of the earth’s rotation starts the winds in the
thunderstorm spinning in a circular motion.
35. At the center of the storm is a calm, often
cloudless area called the eye, where there
is no rain, and the winds are fairly light.
36. The Buildup
As the hurricane builds up it begins to move
It is sustained by a steady flow of warm, moist
The strongest winds and heaviest rains are
found in the towering clouds which merge
into a wall about 12-18 miles from the storm’s
37. Winds around the eye can reach speeds of up
to 125 mph and a fully developed hurricane
pumps out about two million tons of air per
The hurricane travels at speeds of between 10
& 30 mph
When it hits an area of cold sea or land, it
enters a cold, inhospitable climate, where its
supply of moist air is cut off
38. The eye quickly disappears and the storm
begins to die down
Yet it is when it hits the land that a hurricane,
typhoon, or cyclone causes most damage
90% of victims are claimed when the storm
first smashes ashore, bringing with it not only
powerful winds, but huge waves called storm
39. The Storm Surge
The deadly companion of every tropical
storm is the storm surge; the huge mounds of
seawater that are whipped up by the
The first sign is a storm surge can occur
nearly a week before the actual hurricane,
typhoon, or cyclone
Winds move outward much faster than he
storm itself and whip up the sea into waves
up to 5 ft. high along the costline
40. When the storm is about 110 mi. from
land, huge waves driven by its winds
begin to crash ashore
The deafening roar of the surf can be
heard miles inland
This is followed by the most deadly and
destructive element of the surge as the
huge bulge of water that forms beneath
the storm’s eye smashes ashore
42. The Damage
For anyone caught in a hurricane, the
experience is a terrifying one.
Fierce, whirling winds rip across the
countryside, overturning cars and heavy
43. Trees are ripped from the ground, and
whole buildings can be lifted from their
Some of the worst disasters occur near
coastal areas, where stormy seas
contribute to the havoc that is wreaked
44. In 1938, one of the most powerful hurricanes
in history swept through Long Island, New
In just seven hours, the storm killed at least
600 people and destroyed the homes of over
The total damage was estimated at the
enormous sum of one-third of one billion
The storm destroyed26,000 cars and 29,000
miles of electric, telegraph, and telephone
wires and flooded thousands of acres of land
45. One coastal area on the island was so badly it
hit by the hurricane that 200 homes there
were completely swept away
Rescue workers searching for missing people
had to use maps from telephone companies to
identify the sites on which the houses once
46. Are We Causing More?
Hurricanes are sustained by warm, moist air
The countries of northern Europe have a fairly
So why have they been hit by hurricanes in
One theory is that global warming is having
47. As the planet heats up, more parts of
the world are developing the kind of
climate that is ideal for tropical
The gases in earth’s atmosphere act
like the glass of a greenhouse,
trapping enough heat from the sun
to keep the planet warm enough for
48. This is known as the “Greenhouse Effect”. One
of the main greenhouse gases is carbon dioxide.
Other greenhouse gases are methane, water,
vapor, and chlorofluocarbons. The only way we
can prevent global warming is by controlling the
amounts of theses gases that are released into
50. What is weather?
Weather describes the state of the
atmosphere at any particular time.
Weather can be described in terms of
temperature, precipitation (snow, rain &
hail), wind speed and direction, visibility
and cloud amounts.
51. What do you mean by weather
Weather forecasting – the
prediction of the weather through
application of the principles of
physics, supplemented by a variety of
statistical and empirical techniques.
52. The weather forecasting has now become a science and it
is performed by adopting the following procedures (steps)
1. recording of weather data (temperature, pressure,
wind speed and direction, cloud forms, humidity and
precipitation, visibility, storms etc.)
2. collection of weather data from weather recording
(observations centers) stations scattered world over
including both land and ocean surfaces
3. transmission of weather data collected form major
weather stations to sub centers .
53. 4. Compilation of weather data.
5. Plotting of weather data on maps and
daily weather records, synoptic charts etc.
6. Analysis of weather cqharts and maps with
the help of electronic computers etc.
7. Final forecasting of weather and numerical