DaylightQ
DaylightQ[datespec]
gives True if it is daylight from the user's location on the specified datespec.
DaylightQ[locationspec,datespec]
gives True if it is daylight from the specified locationspec on the specified datespec.
Details and Options

- DaylightQ[] makes use of $GeoLocation and $TimeZone to determine your location and time zone.
- Locations can be specified as Entity objects, assuming they represent objects with geographic coordinates or GeoGraphics primitives, or they can be latitude/longitude pairs, assuming degrees as units.
- datespec can be a DateObject expression, a TimeObject expression, a date string or a {y,m,d,h,m,s} date list.
- datespec is assumed to be in $TimeZone, unless it is a DateObject or TimeObject expression with an explicit TimeZone option value.
- locationspec and datespec can be either individual items or lists of them.
- If datespec is a list of dates, then the results will contain EventSeries objects.
- datespec can be specified as {start,end,increment} for compatibility with DateRange specifications.
- DaylightQ[…,inclusionspec] is used to specify how much of the locationspec must be in daylight.
- Possible settings for inclusionspec include:
-
"Everywhere" all of the locationspec must be in daylight "Somewhere" some of the locationspec must be in daylight "Nowhere" none of the locationspec must be in daylight - DaylightQ can accept the following option:
-
"SunAngleTest" (#>0&) function applied to the Sun altitude angle to determine if it is daylight
Examples
open allclose allBasic Examples (5)
Determine if it is currently daylight for your location:
Determine if it is daylight for a specified date:
Determine if it is currently daylight for a specified location:
Determine if it is daylight for a specified latitude/longitude and date:
Determine if it is currently daylight for a specified city and date:
Scope (7)
Dates (3)
Dates can be specified as a DateObject:
Dates can be specified as a date string:
Generate an event series that checks for daylight every 10 days in a year:
Locations (4)
Locations can be latitude/longitude pairs:
Locations can be relevant entities:
Find the Sun's position for multiple locations:
By default, extended locations must be fully in daylight in order to be True:
The default behavior can be overridden to allow only part of the extended location to be in daylight:
Text
Wolfram Research (2014), DaylightQ, Wolfram Language function, https://reference.wolfram.com/language/ref/DaylightQ.html.
CMS
Wolfram Language. 2014. "DaylightQ." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/DaylightQ.html.
APA
Wolfram Language. (2014). DaylightQ. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/DaylightQ.html