latitude of the accident location to determine when the sun rose.  For example, if the sun rose at 6:40 in Washington, D.C. that day, it rose later at points further south and earlier at points further north.   It may be relevant to the crash case if the traffic statute require headlights only between sunset and sunrise.  Local airports are also a good source for visibility info.  Information on visibility due to fog may be available from local commercial and private airports.  Wunderground has historical weather information by location and sunrise/sunset times. A hunting pamphlet for the state may list the sunrise and sunset times for the state.  There are many sources from which we can elucidate weather information relevant to our clients’ cases where there are no reliable “eyewitnesses.”