1. 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.
2. 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.
3. 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.
4. 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.
5. 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.
6. 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.
7. 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
8. 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.
9. 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.
10. 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.
11. 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.
12. 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)
13. 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 earths mantle is Magma. When ever extreme pressure builds in
the mantle, along openings or cracks in weak spots in the earths
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.
14. 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 2,200F. 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
15. Types of volcano Shield volcano lava domes cinder cones
composite volcanoes.
16. 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
warriors shield. Mount Kilauea and Maunaloa in Hawaii are good
examples of shield volcanoes. They are usually found at
constructive or tensional boundaries
17. 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
18. 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.
19. 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.
20. Volcanic eruptions in the sea Though ocean floors are
thousands of miles below the water surface, they also experience
many volcanic activities.
21. 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.
22. How does the inside of a volcano look like?
23. 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.
24. 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.
25. 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.
26. 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.
27. 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.
28. 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.
29. 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.
30. 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.
31. 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.
32. What causes flooding? Rains River overflow Strong winds in
coastal areas Dam breaking Ice and snow-melts
33. 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.
34. 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
36. 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.
37. 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.
38. 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.
39. 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.