LONG EXPOSURE CAN BE DONE AT ANY TIME OF THE DAY
In the day, the use of long exposure creates a motion blur effect on any movement; in this case, human traffic. This is completely different from motion blur created at night as objects are more visible during the day and almost every movement that reflects light can be captured.
At night, the use of long exposure allows you to capture any moving object with lights as light trails. This can be seen on highways, especially during periods of heavy traffic when there are a lot of cars and movement.
There are other effects that long exposures can produce. This particular technique is called panning, and is particularly useful for keeping moving objects in focus. Focus on a moving object and capture it with a slower shutter speed (usually 1/10th of a second) by manually following its movements with your camera. You’ll get a blurred-out background created by the surrounding lights, which keeps the viewer’s attention on the main object.
Lastly, let your imagination run wild with some creative photography art. Just use the flashlight mode of your mobile phone to 'paint' in the dark while the camera is making an exposure, and you’ll get a light painting and a shot that’s unique to you!