Set up a proportion
1 mile/1.6 km = 20,000miles/x
Cross Multiply
x = (20,000) * (1.6)
x = 32,000 kilometers
You should not go into the left side of the roadway when within 100 feet of the crossing. Moreover, you should also turn on your turn signal when within 100 of a turn. These precautions prevent accidents as it makes clear to other drivers what your intentions are and drivers making turns are not endangered.
The answer is reflection.
The drawing is simple but illustrates the concept beautifully.
The zone that gases always accelerate upward is the Luminous flame zone. The fire plume is the column of hot gases, flames and smoke rising above a fire. Gases accelerate upward toward the always luminous flame zone. The luminous flame height is the distance between the base of a flame and the point at which the plume is luminous half the time and transparent half the time.