Video Transcript
Why is it that ultrasonic aircraft
can negatively impact the ozone layer? (A) The aircraft create powerful
sound waves. (B) The aircraft exhaust contains
nitrogen oxides. (C) The aircraft disturb the clouds
of ozone. (D) The aircraft heat up the
ozone. (E) The aircraft exhaust contains
carbon dioxide.
Ultrasonic aircraft travel at
speeds that are faster than the speed of sound. To achieve this, the aircraft must
travel at a speed greater than 1060 kilometers per hour at an altitude of about 18.3
kilometers. At this altitude, the aircraft is
traveling within the stratosphere. The stratosphere is the second
layer of the Earth’s atmosphere that extends from an altitude of 10 kilometers to 50
kilometers. The aircraft is flying just below
the ozone layer, which is where the highest concentrations of the gas ozone are
found within the stratosphere. The ozone layer extends from an
altitude of 20 kilometers to 40 kilometers above the Earth’s surface.
Ozone gas is a trace gas found in
the stratosphere. It is very thinly dispersed at low
concentrations. There are certainly no clouds of
ozone within the ozone layer to disturb, so we can rule out answer (C).
It is true that ultrasonic aircraft
create sonic booms, which are powerful sound waves caused due to their high
speed. Sonic booms do not affect the ozone
layer. Ozone in fact plays a role in
absorbing harmful UV rays from the Sun. Powerful sound waves do not
negatively impact the ozone layer, and this is not a correct response.
At the altitude that the aircraft
is traveling at, the temperature of the stratosphere is around negative 50 degrees
Celsius. This is very cold indeed. At the upper altitude of the ozone
layer, the temperature is approximately negative 15 degrees Celsius. The ozone layer is warmer as the
production of ozone from oxygen creates heat. The heat produced by the jet
engines of the aircraft has little to do with the warming of the ozone layer. This heat will disperse rapidly
into the stratosphere. The aircraft do not heat up the
ozone, and they do not negatively impact the ozone layer in this way. Choice (D) is not the correct
answer.
Jet engines that power ultrasonic
aircraft operate by compressing air and adding fuel. The mixture then burns at extremely
high temperatures. This produces huge amounts of
thrust and large volumes of waste gases. The waste gases include carbon
dioxide, nitrogen oxides, water vapor, sulfates, and a small amount of soot. The nitrogen oxides react with
ozone and deplete it. This can negatively impact the
ozone layer. Carbon dioxide does not react with
ozone in this way.
“The aircraft exhaust contains
nitrogen oxides” is the correct answer.
