Tags: #time #timezones
There is a world-wide 24-hour clock called Zulu time (Z), more commonly called Coordinated Universal Time (UTC).
You will notice all weather maps, radar, and satellite images all have their time expressed in “Z”.
The Zulu term stems from military usage while UTC is the civilian term for this 24-hour clock.
An example of Zulu time/UTC would be:
2020-05-30T09:14:59Z (May 30, 2020 at 9:14:59 UTC)
UTC supports an ‘offset’, which is the difference in hours and minutes between a ‘time zone’ and the UTC. It is used to indicate the local time in a particular time zone.
An example of Zulu time/UTC with a 1 hour offset would be:
2020-05-30T10:14:59+01:00 (May 30, 2020 at 10:14:59 UTC+1)
GMT (Greenwich Mean Time) is a ‘time zone’. UTC is a ‘way of keeping time’ around the world.
GMT is the same as UTC, but GMT is a time zone ‘name’ while UTC is the way time is measured worldwide.
Daylight Saving Time (DST) is a way to make better use of daylight. By moving the clock forward one hour during the summer months, we can enjoy an extra hour of sunlight in the evening when people are more likely to be outside and enjoying activities.
Neither UTC nor GMT ever change for DST.
However, some of the countries that use GMT switch to different time zones during their DST period.
For example, the United Kingdom is not on GMT all year, it uses British Summer Time (BST), which is one hour ahead of GMT, during the summer months.
Summer months being March to October.
So first two and last two months of the year the UK uses GMT/UTC timezone.
Meaning in March the clocks “go forward 1hr”, while in November the clocks “go back 1hr”.