2. •Our earth is surrounded by a blanket of air known
as the atmosphere. The atmosphere is made up of a
mixture of gases. If compared to the diameter of
the Earth, the atmosphere is very thin.
•Our atmosphere can be divided into five layers.
They are held to the Earth by the force of gravity.
There is no actual visible borders between the
layers of air and no drastic changes from a layer to
the next layer. Instead, the change is gradual
3.
4. •We live in the troposphere, the layer closest to the
ground. It is about 10 km in height and contains
75% of the atmospheric gases. Weather occurs here
because this layer contains most of the water
vapor.
•Above the troposphere lies the stratosphere. The
stratosphere extends to the height of 50 km. There
is no cloud here and the air is still. Therefore most
planes fly in this layer of the air.
•The stratosphere contains a thin layer of ozone.
This ozone layers absorbs the harmful ultraviolet
rays from the Sun. These rays cause sunburn and
skin cancer.
5. •Beyond the stratosphere, the air here is very cold
and thin. This layer is known as the mesosphere
and it extends to a height of 80 km. most of the
meteorites are being slowed down and burnt out in
this layer.
•The thermosphere is the fourth layer from the
ground. It is found between 80 km and 700 km
above the Earth. Space shuttles fly in this area.
Aurora lights are found here.
•The furthest layer of the Earth is the exosphere,
where the atmosphere merges into the space.
Satellites are stationed here.
6. •The temperature of the atmosphere varies, depending
the height from the Earth. It rises and falls throughout
the layers of the atmosphere.
7.
8. •Weather refers to the present state of the
atmosphere. It could be sunny or cloudy, windy or
still, wet or dry.
•A complete description of weather includes type of
clouds, measurement of temperature, wind speed
and direction, rain, snow, thunderstorms and the
amount of moisture in the temperature.
9. •Meteorology is the study of entire atmosphere,
including the weather.
•A meteorologist is a scientist who studies the
causes of the weather conditions and also forecast
the weather. He also studies subjects not directly
related to weather, such as the composition of the
atmosphere, the atmosphere of the other planets,
and also the causes of the past and present weather.
10. •A weather forecast is the prediction about the
weather that will be experienced a short period of
time in the future, for example for the next day or the
next few days.
•There are thousands of weather stations around the
world. These stations record the information about
weather. They have instrument to measure
temperature, rainfall, wind speed and direction, air
pressure and humidity.
11. •We are dependent to the weather specially
those who work outdoors. Bad or good
weather has good or bad impact on public
health, agriculture, energy, construction,
transportation, tourism, recreation,
ecosystems and biodiversity.
12. When it is raining heavily, it can be unpleasant to go
outside, but water is essential to life
13. •Severe weather events, such as
cyclones, tornadoes, flash floods,
blizzards, heat waves and droughts
can effect human lives and property.
•Nowadays, weather radar and
satellites are also used to help
predict the weather more accurately.
14. •Weather describes the current conditions
such as humidity, air pressure and
temperature.
•These three factors have great effect on the
formation of cloud rain and wind.
•Air pressure is also known as atmospheric
pressure. Air pressure is the weight of the air
above the given point.
15. •Air pressure is usually measured with a
barometer.
•Changes in the air pressure bring
changes in the weather and make wind
blow.
•Air usually moves from areas of high
pressure to areas of low pressure and the
produces wind.
16.
17. •Humidity is the amount of water vapour in
the air. Relative humidity is the amount of
water vapour that is currently in the air
compared to how much the air can hold at a
specific temperature. Relative humidity is
measured in percentage with 100 % refers to
the saturated air at a specific temperature.
•Instruments used to measure relative
humidity are called hygrometers.
18.
19. •The amount of water vapour the air can hold
depends on the temperature.
•A cooler temperature, the molecules in the air move
slower. This slow movements allows the water
vapour to join together and condense.
•A warmer temperature, the molecules move too fast
to join together.
•Therefore, cooler air holds less water vapour and
has a lower humidity.
20. •The graph below shows the maximum of water
vapour in the air at various temperature.
21. •As the air is heated up, it expands.
Therefore, the atmospheric pressure is
lowered.
•So, the temperature is inversely
proportional to atmospheric pressure.
When the temperature is high, the
atmospheric pressure is lower and vice
versa.
22. •Monsoons, tropical cyclones and thunderstorms
are common weather phenomenon in Asia.
•A monsoon is a term from early Arabs called the
“Mausin” or the season of winds.
•This was in reference to the seasonally shifting
winds in the Indian Ocean and surrounding
regions, including the Arabian Sea.
23. •There are seasonal changes which are
particularly noticed as northeast winds
prevailing in the winter in Southeast Asia and
southwest winds in the summer.
•Monsoons are caused by the fact that land
heats up and cool down quicker that water.
•Thus, in summer, land reaches a higher
temperature that the ocean. The hot air over the
land tends to rise, creating an area of low
pressure.
24. •This creates a constant wind blowing toward
the land.
•As the wind is blown from the sea, a lot of
moisture is collected.
•So, in Thailand, the southwest monsoon starts
in May and ends in September. There is a lot of
rain with higher temperatures and humidity.
25.
26. •In winter, the land cools off quickly, but the
oceans retains heat longer.
•The hot air over the ocean rises, creating a
low pressure area and a wind blowing from
land to ocean
•As the wind is blown from the land, therefore
it contains less moisture.
•So, the northeast monsoon starts in October
and ends in February with the little rain and
lower temperatures and humidity.
27.
28. •A tropical cyclone (or tropical storm,
typhoon, or hurricane, depending on
strength and location) is a type of low
pressure system which generally forms in
the tropics.
•Structurally, a tropical cyclone is a large,
rotating area of clouds, wind and
thunderstorm activity.
29. •The primary energy source of a tropical
cyclone is the release of the heat or
condensation from water vapour condensing at
high altitudes. Because of this, a tropical
cyclone can be thought of as a giant vertical
heat engine.
•A cyclone has a low air pressure area at its
surface and a high air pressure area on top.
•Cyclones cause thunderstorms, high winds
and flooding.
30. •Tropical cyclones play an important role in
the atmosphere circulation system. They
transfer heat from equatorial regions to areas
of higher latitudes.
•A thunderstorm or T-Storm, is a form of
weather characterized by the presence of
lightning and its attendant thunder.
•It is often accompanied by copious rainfall,
hail, or on occasion, snowfall (which is known
as thunder snow)
31.
32. •Thunderstorm forms when significant
condensation, resulting in the production of a
wide range of water droplets and ice crystals,
occurs in atmosphere that is unstable and
supports deep, rapid upward motion.
•In Thailand thunderstorms are common all
throughout the year specially during the
southwest monsoon.
33. •Mild thunderstorms do not cause
much damage and only slightly
affect us. We may have to postpone
a game of a football or seek shelter
inside a building.
34. •Severe thunderstorms and cyclones however are
damaging.
a.Flash flood commonly occur during
thunderstorms. These floods can cause loss of
human or animal life and damage crops and
property. In the cities, motorists may be
stranded in traffic jams that last for hours.
b.Winds can easily reach 80 km/h. in severe
storms, wind velocity is even higher, reaching
more than 90 km/h. such strong winds are
dangerous and cause a lot of damage.
35. c. Thunderstorm may produce hailstones which
can damage property and crops and injure
human and animals.
d. The lightning generated is dangerous too.
Lightning may cause loss of lives and property
damage. Lightning can also start fires.
•If your area is low lying or prone to flooding,
have sandbags or other barriers ready to
prevent flood waters from entering.
36. We already learnt that weather phenomenon is
dangerous.
Let us learn how we can protect ourselves and
our property from dangerous weather
phenomena.
•During storms avoid being out in open fields or
open areas. Always seek shelter inside buildings
immediately.
37. •Be familiar with the locations of big drains
to avoid falling into them.
•Do not drive or operate vehicles.
•Move people and furniture to higher levels.
•Install good surge protectors and lightning
conductors in buildings. Test them frequently
to ensure they work.
38. •Avoid water – based activities such as
swimming, fishing or boating.
•Do not use machinery such as tractors on
farms, road or building construction sites.
•Do not play golf.
•Do not use the telephone, computer or
devices connected to modems.
39. •Do not repair electrical appliances.
•Stay away from windows.
•Stay away from electrical power
transmission lines.
•Move vehicles, outdoor furniture and
other such items indoors.
40. •If your area is low lying or prone to flooding,
have sandbags or other barriers ready to
prevent floodwaters from entering.
•Be familiar with the locations of big drains to
avoid falling in them.
•Do not drive or operate vehicles.
•Move people of furniture to higher levels.
•Install good surge protectors and lightning
conductors in buildings. Test them frequently
to ensure they work.
41. •Weather forecasting is the science of
predicting the state of the atmosphere for
a future time and location.
•The history of weather forecasting goes
back millennia, however the techniques
used have changed significantly since
then.
42. •Today, weather forecasts are made by
collecting as much data as possible about the
current state of the atmosphere and using
understanding of atmospheric processes to
determine how the atmosphere evolves in
the future.
•However, the chaotic nature of the
atmosphere and incomplete understanding of
the processes mean that forecasts become
less accurate as the range of the forecast
increases.
43. •A weather forecasts predicts what the
weather in the future is likely to be.
•Information from the meteorologists
and satellites are analyzed, using
computers, and a station model is
produced.
•A station model shows the weather
condition at a specific location using
symbols.
44.
45.
46. •In addition to the station model,
weather map has lines that indicate the
atmospheric pressure and temperature.
•An isobar is drawn to connect points of
equal atmospheric pressure.
•Weather forecasts are important
because severe weather phenomenon is
dangerous.
47. •When we study weather forecasts, we can
be warned dangerous weather
phenomenon and take the necessary
precautions to avoid loss of life and
property damage.
•Certain economic activities, for example
fishing and agriculture are very dependent
on the weather conditions. Accurate and
reliable weather forecasts are even more
important in these fields.
