Is Nikon d3100 capable of doing these kind of pics?

http://www.smashingmagazine.com/2008/09/07/35-brilliant-examples-of-rain-photography/
http://prestigeportraits.com/gallery.aspx

If not, is it close? I have the 18-55 mm lens will that work?

Are you asking if it will be similar quality? As in the resolution or amount of pixels in the photo? I would say the quality is very similar. I own the d3100 and am very impressed with the picture and video quality. Honestly though, if you're asking about how the photos are edited or composed, (the aesthetic feel or look to the photo), that all depends upon the photographer and the creative choices they make.

If you take the time to learn how to shoot well in terms of technical knowledge, composition, lighting, and subject matter then it won't matter if you have a D3100 in your hands or a D700.It comes down to how well YOU as the user can create a quality image, not the camera.

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and you see what the d3100 is capable of. Now, for some things you'll need a better lens. For all of these you'll need a good eye and photography skills.