Because of the low light during the night - the camera does not receive enough light and the blue haze is actually 'noise'. The sensor switches to higher sensitivity and distorts the image.
Nokia 7110 -> Siemens C45 -> Siemens C55 -> Siemens M55 -> Siemens M65 -> Nokia 6131 -> Nokia N73 -> Nokia N82 -> HTC Wildfire -> HTC Desire HD -> Nokia Lumia 800 + Sennheiser CX 500
If I've helped, use the Kudos button to thank