| Example 1 | Example 2 | |||
|---|---|---|---|---|
| New York | West | ← Greenwich → | East | Beijing |
| 74 W | West | ← Longitude [deg] → | East | 116 E |
| -74 | Negtive | ← Longitude [deg] → | Positive | +116 |
| UTC-5 or UTC-4 | - | ← UTC → | + | UTC+8 |
Given $t_{UTC}$, local mean time $t_{LMT} = t_{UTC} + \frac{lon}{360} \times 24hr$.
For verification, New York is at (40.730610 N, 73.935242 W) or (+40.730610, -73.935242).
New York timezone is Eastern Standard Time (EST) UTC-5 in winter, and Eastern Daylight Time (EDT) UTC-4 in summer.
The calculation based on longitude is $t_{LMT} = t_{UTC} + \frac{-74}{360} \times 24hr \approx t_{UTC} - 4.9hr$, which is consistant with UTC-5.