Duration of Daylight/Darkness Table for One Year
Astronomical Applications Dept. Astronomical Applications Dept.
 
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Important!  Please read the Notes section.

This page provides a way for you to obtain a table of the duration of daylight or darkness for any year between 1700 and 2100.

You can obtain a table for any location worldwide by following these simple steps:

Form A - U.S. Cities or Towns

Specify year, type of table, and place:

  

  

  

The place name you enter above must be a city or town in the U.S. The place's location will be retrieved from a file with over 22,000 places listed. Either upper- or lower-case letters or a combination can be used. Spell out place name prefixes, as in "East Orange", "Fort Lauderdale", "Mount Vernon", etc. The only exception is "St.", which is entered as an abbreviation with a period, as in "St. Louis". You need only enter as many characters as will unambiguously identify the place.

Form B - Locations Worldwide

Specify year, type of table, and place:

  

 

The place name you enter above is merely a label for the table header; you can enter any identifier, or none (avoid using punctuation characters). The data will be calculated for the longitude and latitude you enter below.

Longitude:        
Latitude:        
Time Zone:    
Need coordinates?  Try NGA's GEOnet Names Server (GNS).
Need U.S. coordinates?  Try the USGS Geographic Names Information System (GNIS).
Need a time zone?  Try the time zone map.

Notes

Explanation

The Duration of Daylight table provides, for each calendar date, the total time that any portion of the Sun is above the horizon. Typically (for low and mid-latitude locations), this will be the elapsed time beginning at sunrise and ending at sunset.

The Duration of Darkness table provides, for each calendar date, the total time that the entire Sun is below the horizon. Typically (for low and mid-latitude locations), this will be the sum of two elapsed times: the time beginning at local midnight and ending at sunrise, and the time beginning at sunset and ending at local midnight.

The local times used in these calculations are based on the standard time zone of the location for places in the U.S. (Form A), or the input time zone (Form B).

For definitions of sunrise and sunset, see Rise, Set, and Twilight Definitions in our FAQ area.

For an explanation of why there is generally more daylight than darkness during the equinoxes (and all year at the equator), see Length of Day and Night at the Equinoxes and Comparative Lengths of Days and Nights.

How to Print the Table

The table is 112 characters wide, so to print it you must use landscape orientation and 8-point (smallest) type. Consult your browser's documentation for details on how to change the font/text size. An alternative scheme is to save the table to a file on your computer (for example, in Internet Explorer, click on Page then Save As...), then use your favorite word processor or text editor to print it.

How to Import the Table into a Spreadsheet

Open your favorite text editor, then copy the numerical part of the table (i.e., do not copy the table headings) from your browser and paste it into the text editor. Save the data as a text file.

In Excel 2003, click Data on the menu bar, then Import External Data, then Import Data. Select your saved text file. Choose fixed width in the dialog box. [In Excel 2004 for Mac, the commands are Data -> Get External Data -> Import Text File]

In Excel 2007, click Data on the menu bar, then From Text. Select your saved text file. Choose fixed width in the dialog box.

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