Wednesday, March 29, 2006

DayLight Savings

I was having an argument with my beloved wife on when the daylight saving starts. As usual, she was right..:)..(Okay Shoba, keezha irangu)... Anyway, I found that the Daylight Savings Time (DST) begins at 2 a.m on the first Sunday of April and reverts back at 2 a.m on the last Sunday of October. I also found that, beginning 2007, DST is extended by one month and begins at 2 a.m on the second Sunday in March to 2 a.m on the first Sunday of November. One might ask, whats the big deal about DST. For a long time, I never understood the theory behind it. Some told me that we will get more day light during summer in the evenings for various activities. But, is that the reason?

During the start of DST, time is shifted to the right by one hour. This would mean that, the sunrise and sunset will seem to happen one-hour later than usual. During winter, the time is reverted back by shifting time left by an hour from DST (which is the actual time according to international standards). One of the reasons cited behind this is conservation of energy. If sunrise is shifted a little late, especially during the time when most people are asleep, there is very little impact in the morning. In the evening, since the daylight stays for a longer period of time, people dont use electricity for lighting till late at night. Multiply that savings for the entire nation. Another observation states that, during DST, people tend to drive more during daylight and that causes lesser accidents when compared to night time. Also, since the night time starts a little late, the window from crime which typically happens early on in the night is reduced as well. DST helps you lead a better life at a lower cost..:)

Coming to lighter side of things, when daylight saving happens, any overnight bar should make sure that they close at 1:59AM instead of 2:00AM since that would add one more hour. Also, employees working overnight shifts will end up working 1 hour more than normal and 1 hour lesser than normal during the reversal. One more interesting thing is that, if you want to re-live a moment, the DST start day would be a fine day. You get 1 hour worth of time again. Isnt that interesting? The reversal is interesting as well. You lose an hour worth of stuff in a second. If you plot the time on the x-axis, suddenly you will see a discontinuity of an hour, which in absolute sense is just infinitesimally small... Anyway, I like DST because I can sleep for one more hour and I dont like reversals because I get less sleep. One interesting study would be to find the money lost due to the confusion before and after DST changes and see if the savings are justified...:)

6 comments:

sdpal said...

I knew about the energy saving part.. but working shift closes at 1.59 is new(s) to me.

BrainWaves said...

I never understood daylight saving fully. Reading this makes it clear but still in my mind it is still a mystery.

Another thought came to my mind now. What if, all the clocks are synced everyday morning. So that the change is gradual. That is 30 sec increment for first half of the year and 30 seconds decrement. We live by our clock/watches aren't we?

nourish-n-cherish said...

I've read the theory you mentioned in Para 2 : The only weird thing about it is: Since it is darker earlier than expected in Winter, Accidents should increase, electricity consumption should increase and crime rate should increase too. So, the annual rate should remain the same: less in Summer and more in Winter!

Or am I missing something obvious here?

Suresh Sankaralingam said...

Brainwaves: I think your idea of gradual time was practiced initially when Benjamin franklin proposed it in 1784... Not at the level of seconds granularity. But, 20 minutes or so granularity per week or something like that... So, you are now thinking like Benjamin Franklin... Cool idea though...

Saumya: This is my guess... I think, during winter, the sun rises late and sets early. So, moving the DST back to normal should still utilise the maximum sunlight there is... Just while typing this, I did a quick check to my theory and it seems right...Checkout the following site for sun-rise and sun-set timing for Dec and July...
http://www.sunrisesunset.com/custom_srss_calendar.asp

nourish-n-cherish said...

There is still a problem. Ex: Sunset times in Dec is taking the daylight savings into account. So, if they mention the sunset time as 4:51 p.m., it is actually 5:51 p.m. By doing this, they are actually making sure more time is spent in the dark in Winter.

Suresh Sankaralingam said...

Let me do some math here....

Dec 15:
Sun Rise: 7:13 AM; Sun Set: 4:51 PM

Total hours of Day Light: 10 hours

July 15:
Sun Rise: 5:58 AM; Sun Set: 8:28 PM (DST)
Real Time:4:58 AM; Sun Set: 7:28 PM

Total hours of Day Light: ~ 14.5 hours

If we dont do the reversal to standard time, following will be the sunrise and sunset times during winter

Dec 15:
Sun Rise: 8:13 AM; Sun Set: 5:51 PM

Whichever way we choose in winter, we only have 10 hours of day light. If you compare DST vs Real Time in December (you can choose between 7-5 or 8-6), the Real Time (7-5, Reversal) makes sense to me. I am assuming that me getting up at 9:00AM must be an anomaly..:)