different types of effects in opengl

Dear friends,
I want to render a raining effect,snowfall effect,morning,evening and night effects in opengl.
So please tell me how they are possible.

On AMD documentation web site: For raining effect you can read this file .For sky rendering you can read this file.These two files are on this web page.

On NVidia documentation web site: This file for rain.Check this web page for nature scene with source code. For snow accumulation look at this file.

Remember that the kinds of effects you want to implements are not trivial especially for rain and for snow. The link of the papers I give you should indicate an approximation of the amount of work necessary to implements these.Finally, some of these papers contain references to other papers so google around for more info.