Sunrise Positions in Washington, D.C.
for Equinoxes and Solstices

Latitude 38° 53' N, Longitude 77° 01' W

The Earth's axis of rotation is inclined 23.5 degrees from the vertical (relative to the plane of its orbit around the Sun). This means that the orientation of the Sun's rays at a location changes over the course of the day and the year. As a result, in the extra-tropical regions, we have seasons! The position of the Sun in the sky changes and brings with it, over the year, changes in Duration of Insolation (number of hours daylight) ... and, ... Angle of Insolation (altitude of Noon Sun).

In the following photographs, the top row shows two daytime views of the local horizon (a wider view and a close-up) showing the orientation of the photo site relative to the monuments of Washington, D.C. The green dome of the Jefferson Building of the Library of Congress (to the right of the Capitol) is directly east from the camera position site.

Picture
Orientation
(wider view)		 Due East to
Jefferson Dome
(close-up)

Mar
Jun
Sep
Dec
(Click on any image to view a larger version of the photograph.)

All of the photographs in the second row were taken near the time of sunrise on a clear day near the 21st of the month. The date, local standard time of sunrise, duration of insolation (number of hours daylight), and angle of insolation (altitude of Noon Sun) are listed in the table below.

Sun Information
Astronomical Event Spring
Equinox		 Summer
Solstice		 Fall
Equinox		 Winter
Solstice
Date Mar 21 Jun 21 Sep 21 Dec 21
Sunrise (EST)
(Add one hour to convert Jun & Sep EST to EDT)		 6:09 a.m. 4:43 a.m. 5:55 a.m. 7:23 a.m.
Duration of Insolation (hours:minutes) 12:12 14:54 12:11 9:27
Angle of Insolation (degrees) 51.0 74.5 51.0 27.5

For the complete time-series of photographs (Jan-Dec), visit the Sunrise Positions in Washington, D.C. Web page. For sunrise/sunset times for your location, contact the U.S. Naval Observatory.

© Copyright 1997 Dr. Robert Weinbeck, weinbeck@dc.ametsoc.org