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Why is one side of a sand dune steeper than the other?
Viewed from one end, sand dunes have a flat back side and a steep front side. The wind blows up the back side of the dune. If the wind blows fast enough, it will pick up and transport sand grains up the back of the dune. When the wind goes over the top of the dune, it slows down.
In what direction do dunes move?
These winds are called unidirectional winds because they always move in the same direction, from the southwest to the northeast. As the wind blows, it pushes the sand ahead of it, so individual dunes are slowly moving to the northeast.
Which part of the dune is the most stable?
barchans
Consequently, the most stable dunes over time are barchans and longitudinal dunes (with no external sand supply).
What is the leeward side of the sand dune?
leeward – The side of a dune, mountain, or hill facing away from the wind. slip-face – The steep leeward side of a dune where sand falls as wind moves it over the peak.
What process occurs on the leeward side of a sand dune?
Wind velocity decreases after it blows over an obstacle – some sand is deposited on the downwind side. The steep, downwind face of a dune develops as sand rolls and hops up the gentle windward slope and tumbles/slips down the leeward side (Fig. The process causes the dune to migrate.
What is the tallest sand dune in the world?
Duna Federico Kirbus
Duna Federico Kirbus – Catamarca, Argentina The Duna Federico Kirbus is the highest dune in the world, measuring a whopping 1234 meters in height (2845 above sea level).
Where is the highest sand dune in the world?
To give you an idea of how far out they’re spread, the mighty Duna Federico Kirbus in Argentina is the highest sand dune in the world, while many Namibia holidays, all the way over in southern Africa, also revolve around almighty sand dunes which make this list.
How steep can a sand dune be?
A typical dune is 3 to 100 meters high and asymmetricl. The slip face is usually twice as steep as the windward face (stoss slope) of the dune forms an angle relative to a horizontal ground surface, usually around 33 degrees.
Why does the leeward side of a sand dune the slip face have a steeper slope than the windward side?
The windward side of the dune is gently sloped and bright where the Sun reflects off of it. The leeward side is steep and dark because it lies in the shadow of the dune. This steep slip-face can make a fun slope for sandboarding or sledding.