Page 63 - Design in Nature

Some birds
fly in zigzags
Uplift
from
An waves
inclined
uplift
Asteep
surface
Air rises of hill
along
a hillside
Slope soaring depends on the
movement of air rising to the
hilltop.
The skimmer lacks oil protecting its feathers from
water. Therefore, it does not dive for its prey. Its lower
bill is longer and sensitive to touch. Its wings are Rising
warm air
shaped such that it can fly very close to the surface An air current forming between
of the water for a long time without flapping its wings. the earth and clouds
It dips its lower bill in the water and flies while using
this technique. It captures any prey that its lowered Abird circles on
bill hits. an air current.

Vortex ring type thermal soaring
takes place under the base of a
big cumulus cloud.

Rising in circles

Gliding into the
next current

Wild geese climb up to 5 miles (8 kilometres).
However, at about 3.1 miles (5 kilometres), the Columnar type thermal soaring is
atmosphere is 65% less dense than at sea level. only possible in warm regions.
Abird flying at this height has to flap its wings
much faster, which would require much more
oxygen. In sharp contrast to mammals, the lungs
Abird flies in a straight line
of these creatures have been created to make
best use of the sparse oxygen supply at these
Air columns
altitudes. encountered

Line of uplift
forces

Gust soaring is
possible where two fronts meet.