Better atmosphere.

Code:
    from PIL import Image
    import math
    img = Image.new('RGBA', (64, 1), 'white')
    pixels = img.load()
    for i in xrange(64):
        pixels[i, 0] = (28, 82, 110, 255-int(math.sin((i+1)*math.pi/128)*255))

Signed-off-by: Xiaomao Chen <xiaomao5@live.com>