Phenomena in our surroundings

Looking around any day observe many things. Some of these affect our lives while others do not.

We see birds flying from tree to tree or from house top to house top. This movement of birds does not affect lives. But the passage to time from sunrise to sunrise does. The clouds, rain, wind and the change of seasons all affect our lives in ways more than one.

 

The phenomena we observe locally and from day to day in our very surroundings. These include the weather, climate, length of day, cloudiness, flow of winds, seasons, to mention a few.

 

All the same, the beauty of sunrise and sunset and the apparent passage of the million of twinkling stars and the moon across the night sky never cease to fascinate us. From the sun, we can know directions during the day and from the stars at night. The position of stars in the sky from month to month tells us the seasons, and the phases of the moon are a guide setting dates for a month.

 

Duration of day night

The days are longer in summer than winter and the nights in winter are longer than summer.

 

Day changes

a) On 21st March and 23 rd September, the sun rises at 6 A.M. and sets at 6 P.M. but on sequent days it does not.

b) From March 21 to June 21, the sun rises earlier by a minute or so and also sets later by the same amount of time. This makes June 21st the longest day in the year.

c) There after, the opposite happens-the sun rising late setting earlier each day so that on December 22nd, we have the shortest day and the longest night.

How does variation in length of the day affect our lives?

We know that the longer the day in any part of the earth, the more insolation or sun radiation the earth gets in the part. This makes the season hot.

Again, the length of day and night depends upon the latitude of a place-the difference increase from the equator towards the poles as you know. And how does it affect the climate going northwards or southwards from the equator?

Between the dates, the length of the day decreases or increases according to the position of the earth in its orbit. On September and 21st March, day and night are of equal duration, i, e., 12 hours each, every where in the world.

In the olden days, people used to tell time by the night of the sun in the sky and by the position of the stars in the sky at night. When the sun reached its highest point in the sky it was noon or 12 P.M. The length of one’s shadow was also a rough guide for telling time. On this principle, the sundial was invented. It was in use till the invention of mechanical clocks.

Just as the rising and setting of the sun can be used for telling time, so can be the rising and setting of the different stars at night. With a little practice in observing stars night after night, you can do it easily.


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