This tutorial will help you to create a Shadow and Light effect to your photograph. It is a very interesting tool that I would like to share.
Before: 
After:
Steps to create effect:
1. Open your photo into Photoshop.
2. Find a picture in the public domain (or a picture you own) of a dark cloudy sky. Open the photo into photo shop also.
3. Go to the opened Sky photo in Photoshop. Select and move your photo to the main photo. Place the Sky photo over the entire sky area. Move Sky photo by Edit > Transform > Scale.
4. If your sky is not in the entire photo you would have to blend the line that the photo of the Sky leaves. Do this by adding a Layer Mask. Then go to your Brush tool and select the soft brush. Its opacity should be about 40%. Then brush over the line that the Sky photo leaves, in order to blend it within the rest of your photo. (Although, I obviously did not need to use this with my photo)
5. Stay on your Sky layer and click the down arrow and click Darken (or Multiply, whichever looks best for your photo).
6. Make your Sky layer invisible by pressing the eye button next to it. Go to Channels and make everything invisible except Blue. Right click onto the Blue and duplicate the channel (make sure original Blue turns invisible & the Blue copy is visible). Stay on the Blue copy, and click Image > Adjustments > Levels. Make input levels however you please (I suggest 16, 1.31, 231). Then make visible the rest of the channels yet make Blue copy invisible. Then go back to Layers and make your Sky layer visible.
7. Click Sky and Select > Load Selection. Make sure the Channel is on: Blue copy and that the box next to Invert is checked. (Stay clicked onto the Sky layer) Grab the brush tool and make the color white to then brush over the main object in your photo which you would like to focus on. By doing this, it will make the object lighter and your background darker. Then go to Select > Deselect.
8. To Darken and Lighten some of the areas of your photo, go to New Adjustment Layer. Set levels to however you please (I suggest 37, 1.00, 255). Make Levels: Midtones Darken. Go the Auto: and change around your RGB, Green, Blue, & Red to make the background scene a mysterious and darker color.
9. Grab the Brush tool. To lighten areas of photo put the paint brush on the color Black, and to darken areas put the paint brush on the color White.
10. For final touches, go to Window > Adjustments and change the contrast and brightness of the photo if needed. Grab the paint brush to lighten & darken areas again if needed.
11. Lastly, Flatten your image and go to File > Save As and make sure to save it as a .JPG.
