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G O B A R S P E A K |
PANDITJI
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Hello Panditji…
My niece is 12 years old and she has a project due about changing seasons. I can’t
find anything on the net which explains this concept. It would be great if you could
explain and send me some pictures to go with it.
Nadia, Via Email
DEAR NADIA JI,
The earth tilts 23.45° on its axis. As it rotates around
the sun, various parts of the earth receive different amount of sun's rays. This creates
the four seasons—spring, summer, autumn (fall) and winter. When the sun's rays strike
the earth at 90°, in either hemisphere, it's warm — that's summer. Other places
where the angle is less than 90 it's cooler — that's winter. During spring and
autumn, the earth's axis is pointing sideways and both hemispheres have moderate weather.
Solstices and Equinoxes: The dates of maximum tilt of the earth's
equator correspond to the summer and winter solstice while the dates of zero tilt
correspond to the vernal and autumnal equinox.
Winter solstice: The winter sol-stice is the shortest day of the year
when the sun is farthest south.
Summer solstice: The summer solstice is the longest day of the year
when the sun is farthest north.
Equinoxes are the days when the night and day are nearly the same length and the sun
crosses the equator. When the sun moves northward it's the Vernal equinox when it moves
southwards it's the Autumnal equinox. In the southern hemisphere both the solstices and
equinoxes are reverse as are the winter and summer solstices.
The climatic conditions and seasons differ from place to place. But India has the
unique distinction of being the world's only country with six seasons. Varsha (mon-soon/
rainy season), Sharat (post monsoon), Hemant (pre winter), Shishir (winter),
Vasant (spring) and Grishm (summer).
Hello Panditji...
Which part of India is the largest producer of natural ritha (soapnut tree)?
Sunny, Via Email
DEAR SUNNY JI,
Ritha or soap nut tree is a tropical, large-leaved
deciduous tree, commonly found in Asia. The upper rea-ches of the Indo-Gangetic plains,
Shivaliks and sub-Himalayan tracts are the largest producers of ritha. The tree
needs clayey loam soil with an annual rainfall of 150-200 cm. It thrives in altitudes
varying from 200-1500 metres above sea level.
THE
SEASON ON EARTH |
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I need to make methane gas out of seaweed for a science
expe-riment. Do you have a formula or something like that to help me out?
Chris, Via Email
DEAR CHRIS JI,
Methane gas is also known as biogas. Making methane gas from seaweed in a school lab is
difficult but industries produce it on a mass scale. One common method is through
anaerobic digestion. This means decay of organic material due to the absence of oxygen.
You would need a digester or fermentation tank and a gas holder. The digester is a
cube-shaped or cylindrical waterproof container. The fermentable mix-ture is poured into
it. The gasholder is an airproof steel con-tainer that, by floating like a ball on the
fermentation mixture, cuts off air to the digester (anaero-biosis) and collects the gas
that is generated. The weeds should be stored in a damp, confined space for over ten days.
This initiates anaerobic bacterial action. For more information visit: http://www.unu.edu/unupress/unupbooks/80434e/80434E0k.htm
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