As the raindrop falls, it loses that rounded shape. The raindrop becomes more like the top half of a hamburger bun. Flattened on the bottom and with a curved dome top, raindrops are anything but the classic tear shape. The reason is due to their speed falling through the atmosphere. Air flow on the bottom of the water drop is greater than the airflow at the top. At the top, small air circulation disturbances create less air pressure. The surface tension at the top allows the raindrop to remain more spherical while the bottom gets more flattened out.
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