Archive for the ‘USA’ Category

How does day light saving work?

2012/05/30

If Daylight Saving Time (DST) is not in operation, then during the middle of year (May-Aug), the Sun will rise in UK around 05:00 will set around 19:00.

If we use DST, then clock will go 1 hour forward so that it will appear that Sun rises at 06:00 and sets at 20:00.

This means, you can switch on your lights in your house after 1 hour every evening (well, sort of).

So this will give you one extra hour of daylight every day. For most people it is a benefit.

However, if you have the habit of getting up very early, then you will have to switch on the light (if you get up at 05:00, till 06:00). That means, even though we are saving day light in the evening, we are losing day light in the morning.

As most of the people do their own entertainment in the evening (after finishing off work), it is argued that DST gives more daylight to most number of people. People are expected to spend more time outdoor and likely to buy stuffs till there is light, which indicates a more active economy.

Of course, same benefit can be achieved by re-adjusting opening and closing hours of business, say 09:00-17:00 instead of 08:00-16:00.

Ok, so if day light is saved by making clock fast forward, why not observe the same time thruout the year?

This will cause problem during winter. The Sun will appear at a later time – which will force children to go to school during dark hours in early morning. In fact, this is one argument often used in favor of turning clock back during winter. As clock goes back, the evenings will become darker sooner (e.g. at 16:00 eveything becomes dark when UK follows GMT during winter). That means, all the day light hours saved during summer are lost in winter! Supporters of dual time argues that during winter no body wants to be outside anyway so no harm if it becomes dark sooner. To some extent, it is true.