it contains information on natural disaster

2. Tornadoes are violent storms that strike
as a powerful rotating mixture of wind
and thunderstorm clouds, extending
from the clouds to the ground in a
funnel shape. They are know to be the
most powerful and destructive
atmospheric generated phenomena
and are very common in the USA,
particularly from the middle belt
extending to the east coast.

3.  Every year, there is an average of 800 tornadoes that hit
various parts of the USA. Even though many of them are
very mild and could be seen as just strong winds, there
has been a few tornadoes that have been very
devastating and flattened many homes, schools and
structures along its path.
Tornado incidents are distributed all year through,
forming particularly in late spring (March), with the
most incidents occurring in the summer (May and June),
and reducing in numbers and strengths in the fall.

4. 
Tornadoes occur usually during daytime, from mid-
afternoon till about early evening. Their movement is
usually from the southwest to the northeast.
Sometimes they move in any direction, and in the
general path of the thunderstorm. The spinning winds
cover an area of about 300 — 400 yards, and can
travel on a path for about 5 miles (some tornadoes
travel for over 80 miles), at a speed of about 5 —
60mph.
Sometimes tornadoes develop in a very short time
frame, leaving very little lead time for warning and
preparation.

5. This question is one that has
not been a bit uncertain
among people who study
weather, but here is an
explanation that many
believe is the closest
possible cause of tornadoes.

6.  Step 1: Like all winds and storms, tornadoes begin when the
sun heats up the surface of the land. As the warm, less heavy
air begins to rise, it meets the colder, heavier air above it.
Note that wind shears make it even easier to set them off. A
wind shear is when two winds at different levels and speeds
above the ground blow together in a location.
Step 2: The faster moving air begins to spin and roll over the
slower wind. As it rolls on, it gathers pace and grow in size.
 step 3: At this stage, it is an invisible, horizontal wind
spinning and rolling like a cylinder. As the winds continue to
build up, stronger and more powerful warm air forces the
spinning winds vertically upward, causing an updraft.

7.  Step 4: With more warm air rising, the spinning air
encounters more updraft. The winds spin faster,
vertically upwards, and gains more momentum.
 Step 5: At this stage, the spinning winds, creates a
vortex and the the wind has enough energy to fuel itself.
Step 6: The tornado is fully formed now and moving in
the direction of the thunderstorm winds. When the
pointed part of the tornado touched the ground from
the cloud, it is often referred to as 'touch down' As it
moves it rips off things along its patch.

9.  here are a few examples:
 April 25-28, 2011, USA:
More than 200 tornadoes across Northern Mississippi, Central and
Northern Alabama, Eastern Tennessee, Southwestern Virginia and
Northern Georgia resulted in 316 deaths. 15 of the tornadoes
measured 4-5 on the E-F Scale, with 8 of them traveling for more
than 50 miles. In Alabama, there were more than 2000 more
injuries, with property damage in excess of 4.2billiondollars.
 Tuesday, April 29, 2014, Mississippi, USA:
 On this day, a massive Tornado ripped through Townships in
Arkansas and Mississippi killing at least 34 people. It also caused
various degrees of injuries to 200 more people. Homes were
flattened and trees and cars were flying around

10.  Before a tornado:
Sometimes tornadoes do not give weather readers much time
to get people prepared to take cover. Here are a few things to
do in preparation, especially if you live in a tornado prone
area:
 Always be aware of the safer places (Refuge areas) you can go
to in your home before a tornado visits. If there is no basement
in your home, consider finding a safe place close enough to
your home where you can quickly take shelter. Make sure there
are signs on the walls showing where the closest safe area is.

If there is enough time, grab a few first aid items and stock up
on water and some emergency supplies, that can take you a few
days if things get very bad.

11.  During a tornado:
During an approaching tornado, quickly move to your
basement or designated area if you are in a public place.
These days, schools, hospitals and many business building
have safer places where can take shelter.
 After a tornado:
Lots of injuries occur after tornadoes too. Be careful when
getting out of your shelter as damaged objects and structures
may fall.
Wear safety garments when walking and working through
debris, as there could be broken glasses, exposed nails and
other dangerous chemicals.
Do not touch power lines and objects in water puddles as there
may be live electrical wires around.

12.  The earth's mountains, plains, plateaus, soils,
rocks, etc. as we see it today is believed to
have gone through many phases, with about
80% of it being carved out by the action of
volcanoes.

13.  A volcano is simply a rapture (opening or vent) on the
earth's surface (crust) through which molten magma
(extremely hot mixture of gases, lava, ash and other
burning substances) escape on to the earth's surface.

14. Why do volcanoes erupt?
 Let us start with what the earth is made of:
 The earth is made up of three layer parts. The outer
crust is the layer on which we live. It is estimated to be
about 1800 miles deep. Then there is the mantle; and
then the core (inner and outer core)

15.  The mantle is made up of molten material and gases.
Molten materials are solids (like rock) that have
turned into liquid because of extreme heat. The name
for molten rock and other gases in the earth’s mantle is
Magma.
 When ever extreme pressure builds in the mantle,
along openings or cracks in weak spots in the earth’s
crust an eruption is likely to happen next. During an
eruption, molten materials soon to become lava and
gush out through spaces in the crust to the surface.
Molten rock is called magma when it is inside the crust but once it gets to the surface
of the earth it is called lava.

16.  Eruptions can be in the form of lava fragments
shooting into the atmosphere and forming thick
clouds of lava. Some also flow slowly (non-violent)
from the vent, flooding the area around it. Very fine
particles of ash may also be discharged high into the
stratosphere and further carried away by wind action.
 Fresh lava is believed to be about 2,200°F. It can be red
hot as it shoots from the vent and turn into gray or
black as it cools.. In other types, lava also comes in
thick, pasty form. And this is called volcano

17. Types of volcano
Shield volcano
 lava domes
 cinder cones
composite volcanoes.

18. Shield Volcanoes
 This is very fluid lava, usually from multiple vents or
fractures, spreading over very large areas. The fluid-
like nature of the lava, it does not allow it to pile up
like a cone.
 The result is usually an elevation with a shape like a
warrior’s shield. Mount Kilauea and Maunaloa in
Hawaii are good examples of shield volcanoes. They
are usually found at constructive or tensional
boundaries

19.  They are produced from eruptions with less viscous
lava. Because it is less viscous, they do not spread far
and cool off sooner. This means they pile around the
vent and the dome grows only because of the
expansion of the vent area within.
Lava Domes

20. Cinder Cones
 These are the most common in the study of volcanoes.
When lava is ejected into the air above, the fragments
and fine particles fall as cinders (ash) around the vent,
forming a cone. The height of cinder cones usually
depend on how long the eruption takes and how much
lava comes out. The cone has a depression (crater) in the
middle where the vent is. Cinder cones can rise as high as
1200ft. A good example of a cinder cone is the Paricutin
Volcano in Mexico.

21. Composite Volcanoes
 These are usually awesome in nature, rising up to
about 8000ft and they include Mount Cotopaxi in
Ecuador and Mount Fuji in Japan. They are seen as
massive mountains. They are formed by alternating
layers of ash, rock, dust and lava, (pyroclastic) and
hence the name ‘composite’. They have steep slopes
with a peak.

22. Volcanic eruptions in the sea
 Though ocean floors are thousands of miles below the
water surface, they also experience many volcanic
activities.

23.  In shallow waters, eruptions tend to involve cold water
coming into contact with extremely hot lava from
beneath that ocean floor. The steam escapes high
above the water surface. If the eruptions occur deeper
in the ocean, the weight and pressure of the water
above it suppresses its expulsion and keeps it mild.
This means the ocean floor is not necessarily affected
in any way.

24. How does the inside of a volcano
look like?

25. The effects of volcanic eruptions
Eruptions occurring close to human settlements may spill and
destroy lives and property. People often have to be evacuated.
Example: Chaparrastique volcano in El Salvador started erupting
on 29 Dec, 2013. Anyone living within 2 miles of the volcano is
evacuated.

26.  Landscapes and natural sceneries can be destroyed
 Ash and mud can mix with rain and melting snow, forming
lahars. Lahars are mudflows flowing at very fast pace
Volcanic gases
 The concentrations of different volcanic gases can vary
considerably from one volcano to the next. Water vapor is
typically the most abundant volcanic gas, followed by
carbon dioxide and sulfur dioxide. Other principal volcanic
gases include hydrogen sulfide, hydrogen chloride, and
hydrogen fluoride. A large number of minor and trace gases
are also found in volcanic emissions, for example hydrogen,
carbon monoxide, halocarbons, organic compounds, and
volatile metal chlorides.

27.  Landscapes and natural sceneries can be destroyed
 Ash and mud can mix with rain and melting snow, forming
lahars. Lahars are mudflows flowing at very fast pace
Volcanic gases
 The concentrations of different volcanic gases can vary
considerably from one volcano to the next. Water vapor is
typically the most abundant volcanic gas, followed by
carbon dioxide and sulfur dioxide. Other principal volcanic
gases include hydrogen sulfide, hydrogen chloride, and
hydrogen fluoride. A large number of minor and trace gases
are also found in volcanic emissions, for example hydrogen,
carbon monoxide, halocarbons, organic compounds, and
volatile metal chlorides.

28. What is an Earthquake?
Simply, earthquakes are the rumblings, shaking or rolling
of the earth's surface. It is usually what happens when two
blocks of the earth suddenly slip past one another, or
break apart from each other as a result of tension caused
by prolonged energy build up.
Earthquakes come in many forms. It can be felt as a shock
under your feet, or may be very powerful and destructive
enough to flatten an entire city. They can happen
anywhere, land or sea.

30. What are the types of
earthquakes?
Earthquakes can come in three main forms, depending
on the plate movements that occur beneath the earth's
surface. They could occur on a Convergent Boundary,
Divergent Boundary or a Transform Fault.

31.  Convergent boundary:
Here, one plate is forced over another plate during
movement creating a thrust fault.
 Divergent boundary:
Here, plates are forced apart each other, usually
forming a Rift Zone. This kind is common in ocean
floors where new floors are created. An example is the
Mid Atlantic Ridge.
 Transform fault:
Unlike divergent and convergent, the plates here slip
by each other. This is also called Strike-Slip.

32. Introduction to Flooding
1. Many of us have this idea that floods (or flooding) is
simply, too much water around your house. People
think that can be fun. Wrong. Flooding is a lot more
than that.
Flooding is extremely dangerous and has the
potential to wipe away an entire city, coastline or
area, and cause extensive damage to life and
property. It also has great erosive power and can be
extremely destructive, even if it is a foot high.

33. What is a flood?
 It is a natural event or occurrence where a piece of land
(or area) that is usually dry land, suddenly gets
submerged under water. Some floods can occur
suddenly and recede quickly. Others take days or even
months to build and discharge.
 When floods happen in an area that people live, the
water carries along objects like houses, bridges, cars,
furniture and even people. It can wipe away farms,
trees and many more heavy items.

34. Floods occur at irregular intervals and vary in size, duration and the affected area.
It is important to note that water naturally flows from high areas to low lying areas.
This means low-lying areas may flood quickly before it begins to get to higher ground.
In this lesson, we shall see more about what causes flooding, the types of flooding,
some effects of floods and what we can do before, during and after floods occur.

35. What causes flooding?
 Rains
 River overflow
 Strong winds in coastal areas
 Dam breaking
 Ice and snow-melts

36.  Rains
Each time there are more rains than the drainage system
can take, there can be floods. Sometimes, there is heavy
rain for a very short period that result in floods.
 River overflow
Rivers can overflow their banks to cause flooding.
 Strong winds in coastal areas
Sea water can be carried by massive winds and hurricanes
onto dry coastal lands and cause flooding. Sometimes this
is made worse if the winds carry rains themselves.

37.  Dam breaking
Dams are man-made blocks mounted to hold water flowing down
from a highland. The power in the water is used to turn propellers to
generate electricity. Sometimes, too much water held up in the dam
can cause it to break and overflow the area. Excess water can also be
intentionally released from the dam to prevent it from breaking and
that can also cause floods.
Ice and snow-melts
In many cold regions, heavy snow over the winter usually stays
un-melted for sometime. There are also mountains that have
ice on top of them. Sometimes the ice suddenly melts when
the temperature rises, resulting in massive movement of water
into places that are usually dry. This is usually called
a snowmelt flood

38. Types of floods
 Flash floods
 Rapid on-set floods
 Slow on-set floods

39.  Flash floods
This kind occurs within a very short time (2-6 hours, and
sometimes within minutes) and is usually as a result of heavy
rain, dam break or snow melt. Sometimes, intense rainfall from
slow moving thunderstorms can cause it. Flash floods are the
most destructive and can be fatal, as people are usually taken by
surprise. There is usually no warning, no preparation and the
impact can be very swift and devastating.
 Rapid on-set floods
Similar to flash floods, this type takes slightly longer to develop
and the flood can last for a day or two only. It is also very
destructive, but does not usually surprise people like Flash
floods. With rapid on-set floods, people can quickly put a few
things right and escape before it gets very bad.

40.  Slow on-set floods
This kind is usually as a result of water bodies over
flooding their banks. They tend to develop slowly and
can last for days and weeks. They usually spread over
many kilometers and occur more in flood plains (fields
prone to floods in a low-lying areas). The effect of this
kind of floods on people is more likely to be due to
disease, malnutrition or snakebites.

41.  Economic
During floods (especially flash floods), roads, bridges, farms,
houses and automobiles are destroyed. People become homeless.
Additionally, the government deploys firemen, police and other
emergency apparatuses to help the affected. All these come at a
heavy cost to people and the government
 Environment
The environment also suffers when floods happen.
Chemicals and other hazardous substances end up in the
water and eventually contaminate the water bodies that
floods end up in. In 2011, a huge tsunami hit Japan, and sea
water flooded a part of the coastline. The flooding caused
massive leakage in nuclear plants and has since caused high
radiation in that area.

42.  People and animals
Many people and animals have died in flash floods. Many
more are injured and others made homeless. Water supply
and electricity are disrupted and people struggle and suffer
as a result. In addition to this, flooding brings a lot of
diseases and infections including military fever,
pneumonic plague, dermatopathia and dysentery.
 ...But...
There is also something good about floods, especially those
that occur in flood plains and farm fields. Floodwaters
carry lots of nutrients that are deposited in the plains.
Farmers love such soils, as they are perfect for cultivating
some kinds of crops.