If you go to the ocean during
the night, the voices of
people far away can be heard
clearly. You may wonder, is it
because it is quieter at night
than in the daytime? However,
it is only one of the reasons.
Actually, sound transmits
farther at night may be
related to refraction of sound
waves! First, sound is the
vibratio
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If you go to the ocean during
the night, the voices of
people far away can be heard
clearly. You may wonder, is it
because it is quieter at night
than in the daytime? However,
it is only one of the reasons.
Actually, sound transmits
farther at night may be
related to refraction of sound
waves! First, sound is the
vibration of air, and it is a
kind of wave motion. The
propagation of sound wave is
faster in hot air and slower
in cold air. Therefore regions
of air at different
temperatures have different
refractive indices, just like
media with different optical
densities. When sound wave
propagates in air whose
temperature changes with
altitude, refraction of air
happens. Sound will move
towards areas with lower
temperatures. In the daytime,
when the sun shines the earth,
the air near the earth surface
is hotter than the air above.
Sound waves will be refracted
to the sky. On the contrary,
in the nighttime, the air near
the surface is cooler and
sound waves are refracted to
the earth surface.

Category Travel & Places

Tags Falling, Up, Moonlit