We are experiencing our wet
season hence this post. In Ghana we normally get the major wet season in May
and June, and the minor one in September and October or so. For the past two
days it has been raining to the point that some areas in the capital are being
flooded. Today, even as I pen this post it looks like rain.
As an average person do you know
how and why it rains? Do you know the processes and chemistry of raining? Have
you ever heard of the water cycle?
WATER CYCLE
The water cycle is the key to understanding
the process of raining. What then is the water cycle? The water cycle is the
cycle through which water is sustained in the natural environment. It starts
when water from the oceans evaporates (water turns into a gaseous form or water
vapor) into the atmosphere to form clouds. Evaporation occurs as a result of
heat from the sun. Trees also release vapor into the atmosphere to form clouds.
When the water vapor cools down it turns into liquid water again- condensation.
The release of the liquid water from the clouds is triggered by gravity. The liquid water falls back into the water
bodies (seas, lakes, oceans etc.) for the continuation of the cycle. The
release of liquid water from the clouds is called precipitation.
We then get a sequence: water vapor→ clouds →
condensation→ precipitation→ oceans etc.→ water vapor.
 |
| Water Cycle |
It rains because water vapor stored in clouds cool down to
turn into liquid water again, and then subject to gravity the liquid water
falls in droplets. The falling of the water is called precipitation.
DEFINITION
Rain is liquid water that drops,
subject to gravity, from clouds, as a result of the cooling of the water vapor
in the atmosphere. Rain replenishes fresh water on planet Earth. Rain is used
in the generation of electricity- in Ghana sometimes when we don’t get enough
rain it affects power supply from the Akosombo dam, resulting in dum sor. Dum
sor means power rationing or load shedding. Rain is used in growing crops.
Rain is a compound comprising of
two elements. The two elements are hydrogen and oxygen. Chemically two atoms of
hydrogen combine with one atom of oxygen to form water. Water has three states
namely liquid, solid and gas. In this post I have mentioned water in two
states- water vapor (gas) and oceans (liquid). The third state (solid) is ice.
Hydrogen and oxygen are just two of the many elements that constitute the
natural environment.
RATES AT
WHICH RAIN FALLS
Light – 2.5 mm or 0.098 in. per
hour
Moderate – 2.5 mm to 10 mm or
0.098 in. to 0.39 in. per hour
Heavy – 10 mm to 50 mm or 0.39
in. to 2.0 in. per hour
MAGNITUDE
|
NO
|
CATEGORY
|
PLACE
|
LEVEL
|
|
|
inches
|
millimeter
|
|||
|
01
|
Highest average annual
|
Mawsynram, India
|
467.4
|
11870
|
|
02
|
Highest in 1 yr.
|
Cherrapunji, India
|
1042
|
26470
|
|
03
|
Highest in 1 month
|
Cherrapunji, India
|
366
|
9296
|
|
04
|
Highest in 24 hrs.
|
La Reunion Island, India Ocean
|
71.8
|
1820
|
|
05
|
Highest in 12 hrs.
|
La Reunion Island, India Ocean
|
45.0
|
1140
|
|
06
|
Highest in 1 min.
|
Unionville, Maryland, USA
|
1.23
|
31.2
|
ACID RAIN
I assume you know that by the
activities of man the natural environment is being subjected to harm. Acid rain
is one such harm. I have hitherto shown how and why it rains. I have indicated
that water vapor, a gaseous form of water is released into the atmosphere
through evaporation. It is not only water vapor that is released into the
atmosphere.
Through the activities of man
other gases are released into the atmosphere. Some of the gases are sulphur
dioxide and nitrogen oxide. These gases come from the burning of fuel. The
smoke that vehicles release from their exhaust pipes is an example. The gases
released into the atmosphere through the burning of fuel react with the droplets
of water in the cloud, which precipitate as rain.
The sulphur dioxide and nitrogen oxide I have mentioned react
with the water droplets to produce sulphuric and nitric acids! The droplets in
the cloud which is to precipitate is now polluted with sulphuric acid and nitric
acid. The resultant rain is the acid rain.
Acid rain has negative effect on
the natural environment. Acid rain causes harm to soil, rivers and living
things. When the acid rain falls on planet Earth some of the acid rain goes
directly into rivers, lakes, oceans etc. and some fall on the soil. When the
acid rain falls into, for example, lakes, it increases the acidity of the water
thereby negatively affecting life forms in the water. Shrimp, snails, salmon
etc. are life forms that take the brunt of such increase of acid in water. Some
young fish get deformed in such situation. For example, in Scandinavia there
are lakes that have no aquatic life at all- dead. When acid rain enters the
soil it washes away nutrients and minerals needed for plant growth. Also, it
releases harmful substance like aluminum into the soil.
SUMMARY
Water vapor from plants, rivers,
oceans, lakes etc. form clouds in the atmosphere which cool down to form droplets
of liquid water which falls as rain.
In the case of acid rain gases
like sulphur oxide and nitrogen oxide in the atmosphere react with the water
droplets in the cloud to contaminate them with sulphuric acid and nitric acid,
the resultant rain is acid rain.
PARTING SHOT
To restore and maintain a clean and balanced
natural environment, man has to acknowledge their proclivity to harm the
natural environment, and on the scale they are doing it, and then come up with
a universally acceptable and compliable reversal strategy for restoration and
maintenance. Acid rain adds to the many ways by which the natural environment
is being made dirty, and knocked off balance.
Reference:
http://webprojects.oit.ncsu.edu/project/bio183de/Black/chemreview/chemreview_reading/acid_rain.html
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