If you take a pebble with a radius of about one centimeter and you throw it off a high building, it will reach a speed which will not exceed 75 miles per hour because of the air drag.
如果拿一个半径是，1厘米的小卵石，从高楼上扔下去，它的速度因为空气阻力，不过超过每小时75英里。
2
Creatures within a radius of 30 feet per point of Charisma modifier (minimum 30 feet) are subject to the effect if they have fewer Hit Dice than the initiate (dragons are immune to the effect).
By the calculation it is found that the decreasing radius is all the same for different particle radius at per unit time when the spherical sample particle is evaporated.