1. Thunderstorms

2. Thunderstorms
Thunderstorms are small, intense weather systems
that make strong winds, heavy rain, lightning, and
thunder.
Thunderstorms can happen anywhere with two
conditions: the air near the Earth's surface must be
warm and moist (with lots of liquid), and the
atmosphere must be unstable.100 lightning bolts hit
the earth every second, and at any one moment,
about 1,800 thunderstorms happen around the earth

3. Wind and Rain Somewhere
At any given moment around the world, hundreds of
thunderstorms are occurring. Many of them feature
nothing more than a moderate breeze, heavy rain for
a short while, and some lightening and thunder.
Occasionally, however, these storms seem to run
amuck and become violent; dropping heavy rains
which cause flooding, producing hail that damages
crops and property, and spawning tornadoes , and
surface winds of more than 160 km/h.

5. Convection Currents
Convection refers to the
vertical transport of
physical properties of a
substance due to
instability.
A good example of
convection is the rising
bubbles in a pot of boiling
water.
Another example is a
cumulus “fair weather”
cloud. Cumulus clouds
are the puffy white
clouds and resemble
cotton balls.

6. Rising Warm Air Mass
As the warm air rises through the unstable
environment, the air begins to cool.
When the air has cooled sufficiently, and the relative
humidity reaches close to 100%, the moisture in the
bubble begins to condense.
When condensation occurs, gaseous water vapor is
converted to liquid water droplets, and the droplets in
the bubble become visible. This visible water that has
condensed is what we see as a cloud.

7. The Recipe of a Thunderstorm
All thunderstorm require three ingredients for their
formation:
Moisture :T here must be an abundant source of moisture
in the lower levels of the atmosphere.
Lifting Action : Some mechanism must lift the air so that
the moisture can condense and release latent heat.
Instability : The portion of the atmosphere through which
the cloud grows must be unstable.

8. Stages of a Thunderstorm..
The thunderstorm has 3 distinct stages
 Cumulus Stage.
The formation of fluffy clouds
 Mature Stage.
Severe rain, thunder
 Dissipating Stage.
Fading stages of thunderstorm

9. Cumulus Stage
Cumulus clouds that
exhibit the vertical
development necessary
for thunderstorm
formation are called
cumulus congestus, or
towering cumulus.
The main feature of the
cumulus stage is the
updraft within the cloud.
As the updraft continues
upward, the storm grows
horizontally, and
vertically.
The updraft may extend from
close to the earth’s surface to
several thousand feet above
the cloud top.
As the updraft continues, the
cumulus cloud becomes a
cumulonimbus cloud. The
cloud droplets increase in
size.

12. The Thunderstorm Grows
As the cloud droplets grow into raindrops, they
become too heavy for the updrafts to hold
them; rain begins falling out of the cloud, the
storm enters what’s known as the mature
stage.
The towering cumulus cloud has grown into a
full-blown thunderstorm, and has become a
cumulonimbus cloud.
The top of the storm may penetrate so high into
the upper atmosphere that the top may be
blown away by the jet stream.
This top is called the anvil top, because of its
flat anvil-like shape.

14. Rain causes more Updraft..
As the raindrops begin falling through the cloud,
they drag the surrounding air down with them.
This produces a downdraft in the thunderstorm
cloud, which serves to destroy the updraft that
created the cloud in the first place.
The speed of the downdraft can reach up to
2,500 feet per minute, or higher. (30 mph)

15. Mature Stage
At the bottom of the cumulonimbus cloud,
the air is being forced down by the
downdraft caused by the falling rain.
As the air leaves the bottom of the cloud,
it begins to fan out as it encounters the
surface.
This spreading out of air causes strong
and gusty surface winds, capable of doing
serious damage.
This outward motion of the
downdraft causes gust
fronts to form and move
away from the main
thunderstorm column.
In the mature stage, nearly
equal updrafts & downdrafts
exist side by side in the
cumulonimbus cloud.

17. Dissipating Thunderstorm
As the mature stage of the thunderstorm progresses, the
downdrafts continue to develop, and the updrafts are weakened.
The supply of warm, moist air runs out because the cool
downdrafts cool the area from which the storm
draws energy.
However, the downdrafts spell the death of the thunderstorm.
Without the updrafts to drive the cloud formation, the rain
gradually subsides, and the storm loses its power.
The storm may still be producing characteristic thunderstorm
weather; hail, heavy rains, tornadoes etc.

19. Types Of Thunderstorms..

20. Single-cell Thunderstorm
 Often called “popcorn” convection, single-cell thunderstorms
are small, brief, weak storms that grow and die within an hour
or so. They are typically driven by heating on a summer
afternoon. Single-cell storms may produce brief heavy rain and
lightning.

21. Multi-cell Thunderstorms
 Multicell thunderstorms are storms that have some
organized structure, making their lifetime longer. Multicell
storms consist of several cells of storms, which occur one
after another: each cell has a lifetime of 30 to 40 minutes,
typically. In severe multicell storms, there are usually
several cells active at any one time.

22. Supercell Thunderstorms
 A supercell is a thunderstorm characterized by the presence of
a mesocyclone: a deep, persistently rotating updraft.[1] For this
reason, these storms are sometimes referred to as rotating
thunderstorms
 Supercells are the overall least common and have the potential
to be the most severe.
 Supercells are often isolated from other thunderstorms, and can
dominate the local weather up to 32 kilometres (20 mi) away.
 Supercells can produce large hail, damaging winds, deadly
tornadoes, flooding, dangerous cloud-to-ground lightning, and
heavy rain.

24. Thunderstorm Detection…
Satellites
Most areas of Earth can be seen by weather
satellites. Satellites take pictures of Earth at
regular intervals from space.
Meteorologists watch these pictures over time
to watch for rapidly growing clouds, a clue to
a possible thunderstorm. Satellites also can
tell us the temperature of clouds. Clouds with
cold tops are usually very high up in the
atmosphere, and cold means the cloud is tall
enough to be a thunderstorm.

25. Thunderstorm Detection…
Radars
Weather radar is very important to meteorologists
because it can detect rain and severe weather
even when it is cloudy or dark.
Doppler radar sends out electromagnetic wave
fields that can be reflected back to the radar by
things in the air like precipitation. The amount of
energy that is reflected back can tell us how
heavy the rain might be or tell us there is hail.
Doppler radar can also show us how the wind is
blowing near and inside the storm. This is helpful
in understanding what kinds of hazards the
thunderstorm might have (tornado, microburst,
etc.) associated with it.

27. What Kinds Of Damage
Can A Thunderstorm
Cause???

28. Under the right conditions, rainfall from thunderstorms causes
flash flooding, killing more people each year than hurricanes,
tornadoes or lightning

29.  Lightning is responsible for many fires around the world each year, and
causes fatalities.

30. Hail up to the size of softballs damages cars and windows, and
kills wildlife caught out in the open.

31. Strong (up to more than 193 kmph) straight-line winds associated with thunderstorms knock
down trees, power lines and mobile homes.

32. Tornadoes (with winds up to about 300 mph) can destroy all but the best-
built man-made structures.

33. Microbursts
 A microburst is a localized column of sinking air (downdraft) within a
thunderstorm and is usually less than or equal to 2.5 miles in
diameter. Microbursts can cause extensive damage at the surface,
and in some instances, can be life-threatening.

35. What to DO at the time of
thunderstorm???

40. Thank
you…