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Movement of the Sun in the Sky

Weather phenomena are driven by the sun. Of course the atmosphere and the Earth’s surface have a big role to play. The length of the day and whether or not the sun gets high in the sky at noon decides which days are cold and which are hot. The writeup “The role of the sun” elaborates these concepts.

Many simple observations can be made to determine the Sun’s movement in the sky at a given location. Some of these are:

  1. Observe the sun rise. Note down the direction in which the sun rises with reference to some landmark. Likewise, note down the direction in which the sun sets again using a landmark. Repeat this activity once a week for an entire year. Remember to make all observations form the same point every time. On a sheet of paper, mark out East – West – North – South. Mark the sunrise and sunset directions on this paper corresponding to each observation you made. Does the sun rise in the same place every day? What do your observations show? Why do you think this happens?
  2. Fix a straight stick on a field. Observe its shadow at 12 noon once a week; say on every Monday, for an entire year. Record your observations on a sheet on which you have marked the directions - East – West – North – South, During which month was the shadow the shortest? When was it the longest? In which direction was the shadow pointing? Was there any day when you found no shadow at all? What does it tell you about the sun's movement?
  3. Look up the newspapers or the almanacs and obtain the sunrise and sunset times of your city. If your city is not listed, find out the latitude and longitude of your city/village and use this website: http://largeformatphotography.info/suncalc/ to find out the sunrise and sunset times for an entire year. For each day, calculate the number of sunlight hours. This will give you the duration of day. Calculate the duration of night. Tabulate your calculations. What pattern do you see? Why?
  4. Use the data given below to compare your city/village with other cities in India. What inferences can you draw about the weather in these places?

 

Month
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Day Length
Latitude
                       
23.5 N
10:43 11:06 11:42 12:24 13:02 13:30 13:34 13:12 12:35 11:55 11:15 10:48
0
12:07 12:07 12:07 12:07 12:07 12:07 12:0 12:07 12:07 12:07 12:07 12:07
23.5 S
13:34 13:10 12:33 11:50 11:13 10:47 10:43 11:03 11:39 12:19 13:00 13:29

 

Month
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Max Alt
Latitude
                       
23.5 N
43 49 59 71 82 89 90 84 74 63 52 45
0
67 73 83 85 75 68 67 72 82 86 75 68
23.5 S
90 84 74 62 51 44 43 49 59 70 81 88

Source: http://largeformatphotography.info/suncalc/

 

Tropic of Cancer: Corresponds to the latitude of 23.5 degree North.

Tropic of Capricorn: Corresponds to the latitude of 23.5 degree South.

The day length is given in hours:minutes

Altitude: The vertical angle between the horizon and the Sun. Values are between 0 and 90 degrees.

Note: Children of classes III-V are too young to be able to independently draw inferences, setup hypothesis or make predictions. Beginning with simple conclusions, gradually help them build their inferences. The emphasis in such projects should be more on children participating and enjoying the activities, rather than building conceptual knowledge, especially with regard to complex phenomena like weather.

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