Virtual Academy for the Semi Arid Tropics

1
Virtual Academy for the Semi Arid Tropics
In the Lesson 1 of this Module weather
forecasting is explained briefly. The second
Lesson in this Module is about ways to predict
drought occurrence.
2
Lesson 1 What is weather forecasting ?

• After completing this Lesson you have learned to
  answer
• What is weather forecasting?
• How weather is predicted?
• How reliable is this weather forecasting?
• What is the time span for forecasting different
  weather elements?
• What types of weather forecasting exists?
• What is 24 to 48 hours forecast for agricultural
  operations?

3
Lesson 1 What is weather forecasting ?

• After completing this Lesson, you have learned
  to answer
• What is 5-days forecast for agricultural
  operations?
• What is 30-days forecast for agricultural
  operations?
• How can we get information about weather
  forecasting?
• What simple techniques for predicting weather are
  available?

4
Lesson 1 What is weather forecasting?

• Weather forecasting is a prediction of what the
  weather will be like in an hour, tomorrow, next
  week or during a season.
• Weather forecasts, such as
• "Look for cloudy skies with afternoon
• thunderstorms and a high of 380 C"
• provide critical information about the
  weather to come.

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Lesson 1 What is weather forecasting?

• How weather is predicted?
• Weather forecasters collect data on atmospheric
  conditions, including temperature, humidity,
  pressure, wind speed, and its direction etc.
• High-speed computers, meteorological satellites,
  and weather radars are tools used to collect the
  weather data.
• Such data are fed into the sophisticated
  computers to interpret the weather conditions.

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Lesson 1 What is weather forecasting?

• How weather is predicted?
• Weather forecasting is a very important activity
  of Indian Meteorological Department (IMD).
• IMD provides very comprehensive forecasting
  services for different users.
• IMD has forecasting offices at its 6 Regional
  Meteorological Centers and Meteorological Centers
  at the State capitals.
• In addition it has two major forecasting centers
  at New Delhi and Pune.

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Lesson 1 What is weather forecasting?

• How weather is predicted?
• Indian Meteorological Department (IMD) maintains
  a countrywide network of observational stations
  from where weather reports are received at Pune
  through the Regional Telecommunication Hub based
  at New Delhi.
• With the help of these reports and other
  observations from the globe, the Pune office
  issues the All India Daily Weather Bulletin and
  Weather Forecasts for the entire country.

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Lesson 1 What is weather forecasting?

• How reliable is this weather forecasting?
• Atmospheric conditions change rapidly.
• Hence, even with sophisticated computer models,
  satellite images, and monitoring stations across
  most of the planet, forecasts can be not exact.
• That is, sometimes the weather is more
  predictable than at other times.

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Lesson 1 What is weather forecasting?

• How reliable is this weather forecasting?
• Weather forecasts are usually
• Fairly accurate for the coming 1 to 2 days
• Accuracy of weather forecasts decreases as the
  lead-time increases to 3, 4, or 5 or more days
• A forecast for 4 days often needs to be revised
  as that day approaches, and in some cases the
  revision may be large.
• At lead-times of 5 to 7 days there is only a
  small amount of accuracy in weather forecasts.
• Over 7 days there is nearly none.

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Lesson 1 What is weather forecasting?

• What is the time span for forecasting different
• weather elements?
• Weather element Forecast
• Heavy rainfall, Thunderstorms 24 hours in
  advance
• Wind velocity, Rainfall amount 36 hours in
  advance
• Occurrence of rainfall, Temperature
• intensity 5 days in advance
• Temperature departure, Rainfall
• departure 3 months in advance

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Lesson 1 What is weather forecasting?

• What types of weather forecasting exists?
• Weather forecasts for can be grouped into
• Short range forecast up to 48 hours
• Extended forecast up to 5 days
• Long range forecast 30 days to the season
• Each type of forecasting has a role to play
  in farm operations and planning of agricultural
  activities.

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Lesson 1 What is weather forecasting?

• Where can I get the information on weather
  forecasting?
• Indian Meteorological Department (IMD) provides
  the information on many features of weather for
  many places in India.
• You can get weather information from the
  following IMD web site
• http//www.imd.ernet.in/main_new.htm
• Click on the above web site and find out the
  details of available weather information.

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Lesson 1 What is weather forecasting?

• Where can I get the information on weather
  forecasting?
• There are other Internet sites which can provide
  the weather forecasting for cities and town in
  many countries.
• For example, the following site provides weather
  forecasting for many countries even on hourly
  basis
• http//wwwa.accuweather.com/world-city-list2.asp?
  countryINregionASIpartneraccuweathergo.x18
  go.y11
• Click on the above web site and find out the
  details of weather information in many towns and
  cities in India.

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Lesson 1 What is weather forecasting?

• Where can I get the information on weather
  forecasting?
• In addition to the weather information from IMD,
  local and national news papers, All India Radio
  Stations, and many Television Channels provide
  information about weather from time to time.
• Additionally, we can get weather related
  information from many Internet web sites.
• http//weather.yahoo.com/forecast/INXX0102.html
  (for world over weather forecast)
•   http//weather.nic.in/current.htm (for weather
  forecast in India)

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Lesson 1 What is weather forecasting?

• Where can I get the information on weather
  forecasting?
• http//imdagrimet.org/ (weather services to
  farmers as bulletins, state-wise information for
  India)
• http//intraagri.mah.nic.in/rain/distdailyrain.as
  p (District-wise weather data for Maharashtra
  state)
• http//agri.mah.nic.in/agri/stat/HtmlArea/raindat
  a_main.html (Searchable weather data for
  Maharashtra state)
• http//dmc.kar.nic.in/monthly.htm (drought
  monitoring cell in Karnataka)

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Lesson 1 What is weather forecasting?

• What is Farmers Weather Bulletin?
• Farmers Weather Bulletins (FWB) are issued for
  broadcast in different regional languages through
  All India Radio stations in the evening programs.
• A second bulletin is issued for broadcast in the
  morning during the rainy season.
• The bulletins are also published in newspapers.

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Lesson 1 What is weather forecasting?

• What information Farmers Weather Bulletin
  contain?
• A summary of past weather,
• District forecast of weather during the next 48
  hours
• Special weather warnings for cyclonic storms,
  etc.,
• An outlook for the subsequent two days on the
  onset of rains, probable rainfall intensity and
  duration, weak or a break in monsoon conditions,
  occurrence of frost, hail, squalls, and other
  conditions.
• Warnings of conditions such as heavy rainfall and
  low temperature that are injurious to plants.

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Lesson 1 What is weather forecasting?

• What information Farmers Weather Bulletin
  contain?
• A summary of past weather,
• District forecast of weather during the next 48
  hours
• Special weather warnings for cyclonic storms,
  etc.,
• An outlook for the subsequent two days on the
  onset of rains, probable rainfall intensity and
  duration, weak or a break in monsoon conditions,
  occurrence of frost, hail, squalls, and other
  conditions.
• Warnings of conditions such as heavy rainfall and
  low temperature that are injurious to plants.

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Lesson 1 What is weather forecasting?

• Are there any simple techniques for predicting
• weather?
• Previously when there was not much of
  technology developed for weather forecasting,
  farmers based their prediction on many
  natural, cultural and social phenomena.
• Some of these techniques are discussed in
  this Lesson.

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Lesson 1 What is weather forecasting?

• Are there any simple techniques for
  predicting weather?
• Yes. You can observe weather using your
  senses
• Sight,
• Touch,
• Hearing, and
• Smell.

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Lesson 1 What is weather forecasting?

• How sight is used for predicting weather?
• Sight is the easiest sense to use when you
  forecast. You use sight when you watch clouds
  to forecast the weather.
• Go outside and look up at the clouds.
  Clouds can tell you many things about
  what the weather will do. 

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Lesson 1 What is weather forecasting?

• Sight
• Thin and wispy clouds found very high in the sky
  point the direction the wind is blowing.
• No precipitation falls from such clouds. They
  are a sign of fair weather for now and the very
  near future. 

Fair weather clouds
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Lesson 1 What is weather forecasting?

• Sight
• Clouds, which are like fuzzy bubbles in long rows
  or strings usually, mean that a cold front is
  coming.
• If it is summertime, warm and humid these clouds
  may turn into thunderstorms.

Possible rain- clouds
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Lesson 1 What is weather forecasting?

• Sight
• Dark and low-hanging clouds covering the whole
  sky bring light to moderate rainfall.

Rain giving clouds
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Lesson 1 What is weather forecasting?

• Sight
• Clouds looking like big cotton balls in the sky
  with very large spaces of clear sky in between
  them normally do not carry any rain.
• But, during summer these clouds can change into
  thunderstorm clouds.

May rain clouds
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Lesson 1 What is weather forecasting?

• Sight
• Tall and wide clouds have heavy rain, thunder and
  lightning.
• If you see these clouds on the horizon, it is
  likely it will rain very soon.

Heavy rain clouds
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Lesson 1 What is weather forecasting?

• Touch is another sense that can be used when
  forecasting temperature and rainfall.
• For example
• You can feel the sun hitting your face which
  indicates the air temperature is high.
• You can feel your face get colder when it is
  raining in the nearby area. Combining with
  cloud watching you can forecast how soon you can
  expect rain in your area.
• You use touch when you use the wind to forecast
  the weather, like in wind forecasting. 

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Lesson 1 What is weather forecasting?

• Touch
• Forecasting the temperature sensing the wind is
  simple.
• But it only works if the wind is strong enough to
  feel it.
• A very light breeze won't tell you much about the
  temperature. 

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Lesson 1 What is weather forecasting?

• Touch
• First, know which direction is north from where
  you are standing.
• When you find north, turn and face that
  direction. The direction behind you will be
  south.
• If the wind is coming from the south, usually it
  means that warmer weather is on its way soon.
• If the wind is from the north, usually it means
  that cooler and dryer weather is on the way.
• East or west moving winds can mean a variety of
  things, which makes it difficult to forecast
  using them.

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Lesson 1 What is weather forecasting?

• Hearing
• Hearing is useful for forecasting the weather.
• When you hear thunder, you know that a storm is
  nearby, even if you didn't see the lightning.
• You can hear the wind blow harder or softer
  through trees or as it whips around your ears.

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Lesson 1 What is weather forecasting?

• Are there any other simple techniques for
  predicting weather?
• Based on certain natural phenomena farmers used
  to predict weather.
• If the spectrum around the sun had a greater
  diameter than that around the moon, they
  predicted rainfall after a day or two.
• If there is an accumulation of clouds in the
  South-east direction in a layered form
  accompanied by winds blowing from the southern
  direction then it is claimed that there will be
  rainfall within a day or two.

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Monitoring Drought
Virtual Academy for the Semi Arid Tropics
This concludes Lesson 1 What is weather
Forecasting - in this Module. If you would like
to check your understanding about weather
forecasting, click Exercise button. In the
next lesson i.e. Lesson 2, prediction of drought
is very briefly explained. Click Lessons
button to select Lesson 2
Exercise
Lessons
Course on Coping with Drought