You can create some pretty great effects in Google Earth by adjusting the sunlight slider. This button looks like this:
1. Turn on the Atmosphere slider - click the above button and you'll see a time slider come up:
2. Drag the slider to desired time - by dragging the slider or clicking on the arrows you can see the time change:
There are a couple other functions that you can use as well:
Enter a specific date and time: Click on the little wrench and you can enter time manually:
Date and Time menu
Click on the magnifying glass and to expand or retract the timeline. You can make it as long as a several days, a single day, an hour, etc.
Timeline slider
3. Great, now what? You can save images and record movies with the atmosphere settings how you like them, so you can get some real beautiful shots, especially of 3D imagery and mountains:
4. Setting Placemarks with Atmosphere - You can set a Placemark with the atmosphere on and it will preserve the date and time.
You can exit the Atmosphere tool, and when you click on a Placemark that you made with the atmosphere on, it will automatically open that date and time
You can create a tour between two times with two Placemarks, and record that tour as a video.