| Singing
Sands, Gobi Desert |
|
| Mongolia |
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| Earth's Natural Wonders in
Asia |
| |
| Length of Singing
Sands: 120 miles (193 km) |
| Maximum height
of dunes: 2,500 feet (800 m) |
Sunset
on the Dunes |
Singing sand, whistling
sand or barking sand is sand that
produces sounds of either high or
low frequency under pressure. The
sound emission is usually triggered
by wind passing over dunes or by walking
on the sand. The sound is generated
by shear stress.
Certain conditions have
to come together to create singing
sand:
The sand grains have
to be round and between 0.1 and 0.5
mm in diameter
The sand has to contain silica
The sand needs to be a certain humidity
The most common frequency emitted
seems to be close to 450 Hz.
Importantly, there are
still scientific controversies on
the details of the singing sand mechanism
(see references). It has been proposed
that the sound frequency is controlled
by the shear rate. Others have suggested
that the frequency of vibration is
related to the thickness of the dry
surface layer of sand. The sound waves
bounce back and forth between the
surface of the dune and the surface
of the moist layer creating a resonance
that increases the sound's volume.Other
sounds that can be emitted by sand
have been described as "roaring"
or "booming".
The particular note
produced by the dune, between 60 and
105 Hertz, is controlled by the rate
of collision in the shear band separating
the avalanche from the static part
of the dune. For spontaneous avalanches,
the frequency is controlled by gravity
and by the size of the sand grains.[1]
| Singing
Sands-Gobi Desert |
|
| |
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The name for the region in Mongolia
is Hongory Els, meaning "Singing
Sands." It refers to noise
made by sand grains as they pass
over each other when wind moves
them across the surface of the
dunes. Unlike most sand particles,
which are coarse and irregular,
the particles of the Singing Sands
are round and smooth. In dry weather
conditions, these particles of
sand rub against each other, creating
an eerie musical sound.
The dunes extend for some 115
miles across the southern Gobi
Desert between Mount Sevrei and
Mount Zuulun (part of the Altali
Range). One of at least 30 singing
sand sites in the world, they
are sensitive to pollution, which
can micro-coat sand grains and
kill the sonic effect. |
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|
| The arid steppes
in this low-oblique, generally
north-looking photograph is a
transition zone between China
(People’s Republic of China)
to the south and the independent
buffer state of Mongolia to the
north. The photograph shows part
of the Huang He (Yellow River)
as it flows north and then east
through the Ordos Desert |
|
The climate of this
margin of the Gobi Desert is characterized
by chronic droughts, hot summers,
and bitterly cold winters. The
only true settlements are found
along the floodplains of the Huang
He where sufficient quantities
of water are available for intensive
irrigated farming. Two distinct
agricultural areas are visible
in the photograph—a highly
cultivated area between the Helan
Mountains (a small, north-south-oriented
range near the southern boundary
of the photograph) and the Huang
He and another farther north where
the Huang He bends east. |
| The city of Baotou
is located east of this second
area, along the northern shore
of the Huang He. Several highly
reflective dry salt lakes are
scattered east and west of the
river. The sizable towns of Yinchuan
and Xincheng are barely recognizable
in the cultivated fields east
of the Helan Mountain along the
southern edge of the photograph.[3] |
| |
|
The name for the region
in Mongolia is Hongory Els, meaning
"Singing Sands." It refers
to noise made by sand grains as they
pass over each other when wind moves
them across the surface of the dunes.
Unlike most sand particles, which
are coarse and irregular, the particles
of the Singing Sands are round and
smooth. In dry weather conditions,
these particles of sand rub against
each other, creating an eerie musical
sound.
The dunes extend for some 115 miles
across the southern Gobi Desert between
Mount Sevrei and Mount Zuulun (part
of the Altali Range). One of at least
30 singing sand sites in the world,
they are sensitive to pollution, which
can micro-coat sand grains and kill
the sonic effect.
The area is also famous for its oases
and abundant wildlife, which includes
wild sheep, ibex, and gazelles, together
with their predators, leopards and
dhloe (wild dog), as well as an abundance
of birds. The most popular oasis is
150 miles from the fossil site at
the famous Flaming Cliffs [4]
