Use geographic coordinates consistently
Latitude is positive north and longitude positive east. Western longitudes are negative. The tool calculates solar direction from those coordinates and the UTC instant; no street address or map lookup is required. Check that a copied coordinate pair has not swapped latitude and longitude.
Use the offset for the selected date
The local clock is converted to UTC using the offset you enter. Daylight-saving changes are not inferred from the location. For example, a location using UTC−5 in winter may use UTC−4 in summer. A one-hour mistake shifts every reported clock time even when the underlying geometry is correct.
Interpret azimuth and altitude
Azimuth runs clockwise from true north: east is 90 degrees, south 180 and west 270. Altitude is the angle above the geometric horizon. Negative altitude is treated as night. The simplified solar calculation omits atmospheric refraction, so near-horizon sunrise and sunset can differ from published observed times.
Work through the sample time conversion
The sample uses latitude 40.7128, longitude −74.006, date 2026-06-21 and UTC offset −4. Entering local hour 13 means 13:00 local time, corresponding to 17:00 UTC. A decimal hour of 13.5 means 13:30, not 13:05. The selected hour controls the snapshot diagram; the daily CSV covers the full entered local date.
If you change the sample to a winter date, verify the applicable clock offset separately. The tool accepts an explicit numeric offset, including fractional-hour offsets, and does not query a time-zone service or infer daylight-saving rules from your coordinates.
Check true direction before tracing shadows
Align scene north with geographic north. A compass reading affected by magnetic declination or nearby metal can rotate your measured scene away from the solar azimuth convention. Compare a clear-day observation at a known clock time before drawing conclusions about a marginal shaded interval. At high latitudes, a date may legitimately contain no sun above the geometric horizon, or no night; a conventional sunrise and sunset pair is not guaranteed.