DaylightQ

DaylightQ[]

gives True if it is currently daylight from the user's location.

DaylightQ[datespec]

gives True if it is daylight from the user's location on the specified datespec.

DaylightQ[locationspec]

gives True if it is currently daylight from the specified locationspec.

DaylightQ[locationspec,datespec]

gives True if it is daylight from the specified locationspec on the specified datespec.

DaylightQ[{{location1,date1},{location2,date2},}]

gives True if it is daylight from the specified locations and dates.

DaylightQ[locationspec,datespec,inclusionspec]

gives True if it is daylight from the specified locationspec on the specified datespec taking inclusionspec into account.

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.
  • Dates can be specified as a DateObject or as a string that resolves to a date.
  • 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

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Basic 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:

Options  (1)

"SunAngleTest"  (1)

By default, it is considered daylight if the altitude angle of the Sun is greater than 0:

The default behavior can be overridden to redefine what is meant by daylight:

Introduced in 2014
 (10.0)