A common crescent-shaped dune with horns pointed downwind is called a barchan dune.
A barchan or barkhan dune is a crescent-shaped dune. Barchan ("BAR-kahn") dunes form in areas with only one wind direction, and little or no vegetation. If conditions were "perfect"—the landscape was flat, winds blew from only one direction, vegetation could not grow, and sand was available but limited —barchan dunes would dominate a sandscape. One of the commonest types of dunes, it occurs in sandy deserts all over the world. Barchans are mostly formed by the wind from one direction and appear convex. They are arc-shaped, significantly asymmetrical in cross-section, with a gradual slope towards the wind sand ridge, and made out of well-sorted sand.
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A.part of a binary system
Answer:
YES, the positive feedback leads to the instability and the negative feedback leads to the stability.
Explanation:
- The melting of the glacier ice is an example of the negative feedback as it being a balance in the amount of the ice and the temperature extremes and therefore is a proper way to check the ice cover and thus he arctic ocean will be balanced by the absorption of the sun heat and the leads to the reduction in the temperatures in the nearby lands. And it's a natural cyclic system of the earth.
Answer:
a) explained the appearance of the sun's rotation with a theory of earthly rotation.
Explanation:
Nicolaus Copernicus gave the model of the solar system , named as the Copernican heliocentrism , in the year 1543 .
According this model, the Sun is placed stationary at the very center of the universe and all the planets are moving in a defined path , with uniform speed .
The model gave modern astronomy a kick start .
Hence , from the question,
The correct statement is a) explained the appearance of the sun's rotation with a theory of earthly rotation.
Answer:
Lightening comes first, and thunder a few short seconds after.
