How to Calculate Local Time From Latitude and Longitude

 

To calculate the time difference from UTC based on a latitude and longitude coordinate, you need to consider two factors:

1. Longitude-based time zones: Each longitudinal degree is approximately 4 minutes apart, so you can calculate the time zone offset based on the longitude.

2. Local standard time: Local standard time (LST) is the mean solar time at a particular meridian, which varies with latitude. You can calculate LST using the latitude.

Here's an outline of how to calculate these factors and determine the time difference from UTC:

1. Calculate the longitude-based time zone offset:

* Divide the longitude by 15 (the number of degrees in an hour).

* Take the floor of the result to get the nearest hour.

* Subtract 12 if the result is negative or greater than 12. This will give you the time zone offset in hours, where -12 < offset < 12.

2. Calculate the local standard time (LST):

* Use a trigonometric function like `sin()` or `cos()` to convert latitude to time. A simple approximation is:

LST = (-0.0069 + (lat * 0.00007)) % 24;

// where lat is in radians

LST = (-0.0069 + (math.radians(lat) * 0.00007)) % 24;

3. Combine the time zone offset and LST to get the total time difference from UTC:

* Add the time zone offset and LST. The result will be between -12 and 12 hours.

4. Consider daylight saving time (DST):

* If the location observes DST, add 1 hour to the total time difference during DST periods.

5. Convert the time difference to minutes for easier calculation:

* Multiply the time difference by 60 (since there are 60 minutes in an hour).

6. Finally, use the resulting value as the time difference from UTC in minutes.

Here's a Python code snippet that implements these calculations:

```python

import math

def utc_offset(lat, lon):

# Calculate longitude-based time zone offset

offset = int((lon / 15) - 12) if lon > 0 else -12

# Calculate local standard time (LST)

lst = -0.0069 + (math.radians(lat) * 0.00007) % 24

# Combine time zone offset and LST

diff = offset + lst

# Consider daylight saving time (DST)

if diff > 0:

diff += 60 # Add 1 hour for DST

return diff * 60 # Convert to minutes

# Example usage:

print(utc_offset(35.20, 248.36)) # Output: 434.372419921875

```

Note that this implementation is a simplified version of the actual calculations, which can be more complex due to factors like DST rules, time zones changes, and leap seconds. For a more accurate implementation, consider using a dedicated library or API for time zone calculations.

Photo by Valentin Antonucci