daylight saving time is what it is called when you turn the clocks back.
daylight saving time is what it is called when you turn the clocks back.
what is it called when you turn the clocks back?
daylight saving time
on october 30, 1983, coincident with the end of daylight saving time, alaska switched in 1983 from four time zones to two time zones. the areas east of yakutat set clocks back two hours to change from pacific daylight time to what had been yukon standard time, , and the time zone was named alaska standard time at the end of november. yakutat only set clocks back one hour on that date. most of the remaining longitudes of alaska left their clocks unchanged on that date, changing from alaska-hawaii daylight time () to the new alaska standard time (). some areas that had been on bering time ( in winter, in summer) such as nome set their clocks ahead yet another hour on october 30, 1983 to adopt alaska standard time (the former yukon standard time), effectively changing their standard time zone by two hours. most of the aleutian islands moved from the bering time zone () to the hawaii-aleutian standard time zone () (until 1983 known as the alaska-hawaii standard time zone).
yukon time zone
general relativity predicts an additional effect, in which an increase in gravitational potential due to altitude speeds the clocks up. that is, clocks at higher altitude tick faster than clocks on earth's surface. this effect has been confirmed in many tests of general relativity, such as the pound–rebka experiment and gravity probe a. in the hafele–keating experiment, there was a slight increase in gravitational potential due to altitude that tended to speed the clocks back up. since the aircraft flew at roughly the same altitude in both directions, this effect was approximately the same for the two planes, but nevertheless it caused a difference in comparison to the clocks on the ground.
hafele–keating experiment