What is Daylight Saving Time (DST)?

Q Why is it in News ?

A The United States Senate unanimously passed a law making daylight saving time (DST) permanent, scrapping the biannual practice of putting clocks forward and back coinciding with the arrival and departure of winter.

Q What does this imply?

A 

• With clocks in the US going back an hour, the time difference between New York and India will increase from the current nine and a half hours to ten and a half hours.
• In the Southern Hemisphere, the opposite has happened, where countries have “sprung forward”, and time difference with India has reduced.

Q What is Daylight Saving Time DST?

A 

• DST is the practise of resetting clocks ahead by an hour in spring, and behind by an hour in autumn (or fall).
• During these months, countries that follow this system get an extra hour of daylight in the evening.
• Because the spring to fall cycle is opposite in the Northern and Southern Hemispheres, DST lasts from March to October/November in Europe and the US, and from September/October to April in New Zealand and Australia.
• Dates for this switch, which happens twice a year (in the spring and autumn) are decided beforehand.
• By law, the 28 member states of the EU switch together — moving forward on the last Sunday of March and falling back on the last Sunday in October.
• In the US, clocks go back on the first Sunday of November.

Q How many countries use DST?

A 

• DST is in practice in some 70 countries, including those in the European Union.
• India does not follow DST; since countries near the Equator do not experience high variations in daytime hours between seasons.
• There is, however, a separate debate around the logic of sticking with an only one-time zone in a country as large as India.

 Q What does this system mean to achieve?

A 

• The key argument is that DST is meant to save energy.
• The rationale behind setting clocks ahead of standard time, usually by 1 hour during springtime, is to ensure that the clocks show a later sunrise and later sunset — in effect a longer evening daytime.
• Individuals will wake an hour earlier than usual, complete their daily work routines an hour earlier, and have an extra hour of daylight at the end.