How to calculate geographical time?

North of the Tropic of Cancer in the northern hemisphere: sunrise in the east in spring and autumn, sunrise in the northeast in summer and sunrise in the southeast in winter.

Algorithm of geographical time: first, make sure what time you are talking about, local time or time zone.

Confirmation method of local time: the maximum solar altitude angle at one place is 65438+02:00 noon, and the maximum solar altitude angle at the next day is 24 hours a day.

A time zone refers to a place located at the central meridian of the time zone.

The difference between the two places is one longitude, four minutes and fifteen degrees an hour.

When we calculate, we often calculate by the area of a place.

1) One point is known and the other point is known: basically, according to the principle of adding east and subtracting west, the difference between several time zones increases and decreases by several hours accordingly. If the value is greater than 24, add a day to the date and subtract 24 from the number. If you don't reduce it, you can keep it for one day, that is, if the date is reduced by one day, add 24 to the number and then subtract it to get the value.

2) There is a termination line: the equator rises at 6:00 and sets at 18:00 all the year round. The longitude of the intersection of the termination line and the equator is 6: 00 or 18:00. Time can be calculated by subtracting the longitude difference between the east and the west.