In a country like India, agriculture is not a commercial activity; it is a livelihood for millions. 60 % of the population is dependent on agriculture for their living. More than 50% of the cultivation is depended on Irrigation from Rain.
The system of wind that brings Rain to India is called Monsoon. No pattern in monsoon has been clearly established and a logically sound weather model for monsoon has not been established. That is the reason, why even after great advancement in science and theory of weather prediction, monsoon prediction remains elusive. Rain forms an important part of water cycle. Rain is responsible for distribution of water on the surface of the earth. Water is an essential ingredient in the formation of life. 70% of Earth surface is covered with water as well as 90 % of the biological bodies consists of water. When scientists look for life in any distant planet, they look for water as the life indicator.
Rain Drops
Clouds form when lighter humid
warm air rises and then cools down enough for some of the water vapor in the air
to condense into tiny water droplets or ice crystals. When there are a lot of
water droplets in a cloud, they join together to make raindrops. Sometimes ice
crystals in clouds melt, and that can create raindrops too. Raindrops are much
heavier than the tiny water droplets found in clouds, so rain falls to the Earth
due to gravity. Only some types of clouds produce rain, including nimbostratus
and cumulus clouds. Nimbostratus is a dark, multilayer cloud, and cumulonimbus
is very tall clouds with anvil-shaped tops.
The creation of rain is a simple
process to understand. The diagram above shows the 5 step process which will be
looked at in more detail in the three examples below. The key to this process is
below: 4 - Eventually, the air and vapor
cools to the point where the vapor condenses, making it visible as clouds.
Relief rain is formed when air is
forced to cool when it rises over relief (or height) features in the landscape,
such as hills or mountains. Frontal /
Cyclonic Rainfall The sun heats up the ground
quickly during the day, creating thunderstorms in the afternoon and evening.
Acid Rain
Robert Angus Smith of England
coined the term acid rain in 1852. Term was recognized in 1972 after 120 years
and slowly the western industrial world became more and more familiar with this
term. It literally implies a change toward more acidic conditions of rain, fog
or snow affecting the lakes, rivers, ground water, soil and forest land. Such
changes may occur as a result of slow geo-biological processes occurring in
nature or faster episodic emissions from volcanic eruptions. Of late, rapid
industrialization all over the globe has resulted in acid forming gases into the
atmosphere. In sixties and seventies this phenomenon assumed alarming proportion
affecting the main industrial countries Acid rain kills aquatic life,
trees, crops and other vegetation, damages buildings and monuments, corrodes
copper and lead piping, damages such man-made things as automobiles, reduces
soil fertility and can cause toxic metals to leach into underground drinking
water sources. Acid rain affects lakes, streams, rivers, bays, ponds and other
bodies of water by increasing their acidity until fish and other aquatic
creatures can no longer live. These toxic metals are bad for human health; high
levels of lead in drinking water may harm people. People who ingest mercury in
tainted fish suffer serious health problems. Most of the frogs and insects also
die when the water reaches pH 4.5. Acid rain also harms vegetation.
It is believed that acid rain damages the protective waxy coating of leaves and
allows acids to diffuse into them, which interrupts the evaporation of water and
gas exchange this stops plants from breathing. This stops the plant's conversion
of nutrients and water into a form useful for plant growth and affects crop
yields. Acid rain can also affect health of a human being. Acid rain causes
toxic metals to break loose from their natural chemical compounds. Toxic metals
themselves are dangerous, but if they are combined with other elements, they are
harmless. They release toxic metals that is absorbed by the water, crops, or
animals and human consume it. These foods when consumed could cause nerve damage
to children or severe brain damage may even result in death. One of the serious side effects
of acid rain on human is the respiratory problem. The sulfur dioxide and
nitrogen oxide emission gives risk to respiratory problems such as dry coughs,
asthma, headaches, eye, nose, and throat irritation. Polluted rainfall is
especially harmful to those who suffer from asthma or those who have difficulty
in breathing. Acid rain can aggravate a person's ability to breathe and may
increase disease which could eventually lead to death.
Scientists in the southern Indian
state of Kerala have begun examining an unusual phenomenon: colored rainfall in
some parts of the state. Its southern and central districts have witnessed
spells of colored rain. Prompting researchers to launch a formal investigation. It all started with scarlet
rain showers on some villages in the southern districts of Kottayam and Idukki.
Similar phenomenon was reported from eight other districts of the state. These
areas witnessed spells of green, yellow, brown and black rains. Scientists from the Trivandrum-based
Centre for Earth Science Studies are now studying the rain waters collected by
local people. The institute's Director, M Baba, said scientists believe the
colored rain was caused by dust from a burning meteorite that threw over 2,000
pounds of extraterrestrial dust into the atmosphere.
The level of sulphur deposition
that an ecosystem can bear without long-term damage from acid rain is known as
the critical load of that ecosystem. These critical loads differ from region to
region, based on the sensitivity of each ecosystem to sulphur deposition. Thus,
one way of judging the potential environmental damage caused by excess sulphur
deposition in different regions is to compare the expected levels with the
critical loads. The predictions for the year 2020 for different countries of the
Asian region using the present model shows a grim picture. Many areas in the
Asian region will cross the critical loads of sulphur deposition. The model
throws up an alarming possibility of excess sulphur deposition in India by 2020,
reaching as high a level as 2-5 grams per square meter annually, over and above
the critical loads! Today, as prospects appear in
Asia, China is most vulnerable to heavy losses to health and property from acid
rain, China relies heavily on coal as a basic energy source, while the Chinese
coal is one of the highest in sulphur content in the world. In some industrial
hotspots of China, the sulphur deposition levels on land are as high as 18 grams
per square meter every year, which is many times above the critical level. By
2020, virtually all of Chinas eastern part and large regions in India will
have to bear sulphur deposition levels between 2 and 5 grams per square metre.
Many industrialized areas of Indonesia, Malaysia, Philippines and Thailand will
also experience sulphur annual deposition levels of 5-10 grams per square meter
by 2020. In some highly industrialized areas of China, the levels would climb to
even 26 grams per square meter a year! An indication can be gained on what might
soon happen in China when we recall what happened in the worst polluted areas of
central and eastern Europe - the black triangle - a few decades ago, with
deposition levels reaching approximately 15 grams per square meter per year.
These levels resulted in premature death of many tree species in an area
covering southwest Poland, northwest Czech republic, and southeast Germany.
Rainfall recording is an
important activity. It tells us about the distribution of rainfall over the
country. The historical recording helps to predict amount of rainfall as well
help to prepare for the worst. There are thousands of stations
throughout the world where rainfall observations and records are made. Included
in such records is the fall of snow, reduced to its equivalent in rain. Rainfall
is measured, in terms of inches or millimeters of depth, by means of a simple
receptacle-and-gauge apparatus or by more complex electrical or weighing devices
placed where eddies of air will not interfere with the normal fall of the
raindrops. In addition to the daily, monthly, and annual totals, the depth of
individual rainfalls and their intensity (amount of rain falling during a
specific period of hours or minutes) and other pertinent facts are recorded. Other measurement like wind
movement, cloud formation, Low and high-pressure area, temperature at different
heights in different locations are measured continuously. Based on the readings
obtained and the previous history, Scientist build Rain Model and continuously
make changes in the model to be able to predict one step better. These readings are taken on
ground, balloon, Rockets and through weather satellites. Infra red and visual
photograph provides information on location height and type of clouds etc.
Under normal circumstances Rain
is welcome. The rain provides relief from heat and provides much required water
for irrigation. Rain in the catchment area provides water to rivers. The snow
fall on the hills stores the water on the hills. The snow melts slowly to
provide water through river. The water absorbed by earth over thousands of years
is a great store hose of fresh water. This under ground water is over exploited
throughout the world and is depilating fast. Very soon the humanity may run out
of usable water long before the petrol is exhausted. When there is too much or too
little rain there is problem. Shortage of Rain, affects
cultivation resulting in starvation deaths. Shortage of drinking water results
in time and effort wasted in collecting water for daily usage. Thus leaving
little time and energy for earning daily bread. Vast land may get converted into
Desert in the long run. On the other hand too much rain
results in floods and flash floods, chocking drainage in town. Killing the
standing crops, Killing animals and spreading disease. Buildings, trees etc. may
crash under continuous pouring rain.
When there is heavy rain people
say its raining Cats and Dogs. But does Cat and Dog really rain ? It may never
rain cats and dogs, but fish, shells, and frogs have indeed fallen from the sky
on rare occasions. In 1984, live six-inch [15 centimeters] flounders (fish)
fell on a London neighborhood. It
is thought that a waterspout had lifted them to cloud level from the Thames
River, then later dropped them several miles away. The fish were probably as
surprised as the people who saw them fall.
More recently, the fishing port
of Great Yarmouth in Norfolk, England experienced a shower of fish on August
6th, 2000. Similar stories are told of
remarkable "showers" from other locations near open water. In one
memorable storm in England in 1844, people held out hats to catch dozens of
falling frogs. Such small creatures, once airborne, might be carried aloft for
an hour or more within the strong updrafts of a thunderstorm.
Different part of the earth
receives rain to different degree from no rain to very heavy rain. Rains are
seasonal where as the water requirement is perennial. Excess water need to be
stored so that it is available when in short supply. The process of rain water storing
for the purpose of utilizing when needed is called Rain water harvesting. Rain
water harvesting was in practice in ancient times. With advent of science water
harvesting was not considered important and ground water and rivers were over
exploited. This has reduced the ground water availability and river have started
drying up. In ancient time rain water was
collected and stored in underground tanks or man made or natural lakes. These
lakes were the life line for the villagers around. In many place rain water is
stored in under ground tanks. Many villages in India have taken to cleaning old
lakes and directing rain water to them in an effort to reverse the process. The Governments in many Indian
states are adopting Rain water harvesting by digging special bore with big pits.
The rainwater is directed to the pits and slowly absorbed by the earth. It is
hoped this process will raise the water table. Though a rough estimate shows
that the water being used is many times more than the water that can be
harvested in a year at least in cities like Delhi. Rain Water harvesting sounds
good to the common sense and is a step in positive direction No positive effect
is likely to be visible for years. Many organizations are providing know how and
making money by fooling the public.
Making more water available by
exploiting the ground water and River water seems to be the only feasible
solution for meeting the needs of ever growing population. Rain water harvesting
by collecting water in lakes etc can help to a great extent in the long run this
could reverse the trend of dropping water table. It is also important to reduce
the requirement and balance the natural availability with our requirement. Requirement of water can be
reduced by controlling the population, a step which the government takes
half-heartedly due to political reason. Government may take hard steps when it
would be too late and nature decides to reduce the population by starvation
death and war due scarcity of water. What can be done in the present scenario is
to identify water requirement for different activity and make those activity
more efficient to use less water. Water requirement per head could be easily
reduced by 30% by the change in habits to reduce water wastage and improved
water disposal methods in the kitchen, taking bath or using flush. Emphasize on
agriculture research specifically to optimize the usage of water for irrigation. Develop effective and economical
methods for utilizing sea water. Apparently research is being done even to
recover water from atmosphere.
Rain and water in general are
important to the survival of living beings. Man as a powerful biological machine
yields tremendous power. The power man yields can be gauged by the following
news Humans
May Surpass Other Natural Forces As Earth Movers News
Source:University Of Maine In 1994, Hooke published the
results in a paper in GSA Today, a journal of the Geological Society of America.
He estimated that on a worldwide basis, humans move more of the planet around,
about 45 gigatons (billion tons) annually, than do rivers, glaciers, oceans or
wind. For comparison, he estimated that meandering rivers may move about 39
gigatons of sediment a year. Others have estimated that rivers deliver about 24
gigatons of sediment to the oceans each year. Even that enormous figure can be
partly attributed to people. Soil erosion from farm fields, construction sites
and other sources contributes significantly to river sediment loads. It is no wonder that the water
resources have been depleted by this powerful biological machine. It is time for
this biological machine to become human and think in terms of survival.
Population explosion is not to be confused with survival, It is suicide. Long live the biological machine.
1 - The sun is the driving force behind the process of convection which is the
main process behind the creation of rain.
2 - The sun heats up the sea and this in turn heats up the air. The sun cannot
directly heat the air. When the water is heated, it turns to water vapor.
3 - As the air is warm, it rises up into the atmosphere, taking the water vapor
with it. As it does so, it cools due to expansion.
5 - Water droplets within the clouds collide and join together to form rain
drops, which fall back down to the sea / ground.
The following examples show three ways that rain is caused. Often, these are
inaccurately referred to as the 'three types of rain'. In fact, all rain is the
same - in these examples, the way the air is cooled that makes these examples
different from each other. The cooling causes the condensation that creates the
rain. Warm air can hold more water than cold air, and this is the key to the
formation of clouds. Other forms of precipitation (such as snow, hail, etc.) are
formed in a similar way, through differences in air temperature and events in
clouds.
Relief / Orographic Rainfall
1 - Air is forced to rise over a hill or mountain. As air rises away from the
heat source (the ground heated up by the sun) the air cools by 1C per 100m.
2 - As the water vapor in the air condenses, it forms clouds and rains. Air that
has cooled cannot hold as much water as warmer air.
3 - The air starts to descend the hill or mountain and begins to warm up again.
4 - As air warms up, it can hold more water and as it has precipitated, the air
has less water overall. Therefore clouds disappear and rain stops. This side of
the relief feature is known as a RAINSHADOW.
In the countries like UK, Frontal
rain is very common. The colder air masses come from the north and the warmer
air masses from the south. When they meet, they form a FRONT (the line between
the air masses - they cannot merge as they have different temperatures).
1 - The colder air mass is more dense than the warmer air mass, so carries on
pushing forward along the ground.
2 - The warmer air mass is lighter than the colder one so is forced to rise over
the advancing cold air mass.
3 - As the air is forced to rise, it cools and water vapor in the air condenses
to form clouds.
4 - Further forcing of the air (now with clouds) upwards causes precipitation to
occur.
Convectional Rainfall
1 - The sun provides the heat source, heating up the ground quickly.
2 - The ground then heats up the air through convection and the air rises very
quickly, carrying any evaporated water with it.
3 - As the air rises it cools very rapidly.
4 - Large clouds develop directly above the rising air as the air cannot hold as
much water.
5 - Torrential rain and thunderstorms are caused when the air is cooled to such
as degree that water droplets collide with each other in the clouds very
quickly. Eventually, the individual droplets become so heavy, the air cannot
hold them and they fall as rain.
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