Climate and Environmental Protection - Decreasing Fuel Consumption and Exhaust Gas Emissions in Transportation - page 229

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Fig. 15.6 Connection between temperature of the ocean's surface and frequency of tropical

cyclones

15.4.2 Impact of Climate Change on Air Traffic

The Earth's atmosphere absorbs 7% more humidity close to the surface per degree
of warming. Feedback from local wind can increase humidity by up to 14%. This
process leads to more tropical storms over sea and land, like hurricanes, cyclones
and tornados; see Fig. 15.6 [ 30 ].
Wind velocities can reach 500 km h -1 (311 mph). Extreme precipitation events
appear more frequently. In the northern hemisphere, the number of short, extre-
mely intensive downpours is increasing. In summary, the number of storms is
constant, but the number of severe storms with lightning strikes is increasing; see
Table 15.2 [ 31 ].
Climate change strongly influences aviation. Cumulous clouds reach altitudes
of 15-16 km (49,180-52,459 ft, i.e., 9.3-9.9 mi) with different electrical charges.
Because of the wide area and the high altitude of storm clouds, airplanes flying in
these air corridors do not have any possibility to fly over these zones.
Positively charged lightning is dangerous even several km from the actual
thunderstorm zone at an altitude from 11 to 12 km (from 36,066 to 39,344 ft or
from 6.8 to 7.5 mi). Their temperature is 30,000C (54,032F) in the lightning
channel and their strike velocity is 100,000 km h -1 (62,150 mph). Although only
5% of all lightning is positively charged, it is more dangerous than negatively
charged lightning because it has particularly intensive discharges with consider-
ably higher current intensities and longer time intervals [ 32 ].
Some composite airplanes also have an additional layer of protection against
lightning strikes by installing Metal Oxide Varistors (MOV) throughout the circuit.
If an MOV senses a sudden surge of current than it is designed to break and protect
the rest of the aircraft's delicate electronic systems [ 33 ]. Aircraft design principles