The Hills cloud is a hypothetical inner region of the Oort cloud with an outer boundary of 2-3×104AU, and a less well defined inner boundary at 50 to 3000 AU, proposed in 1981 by J. G. Hill. It was suggested as a source that delivers comets to a relatively tenuous outer Oort halo, resupplying it as the outer halo is depleted by closely passing stars or gigantic molecular complexes and by galactic tidal effects. It is predicted that it has one to two orders of magnitude more cometary nuclei than the outer halo. This image is an artists rendering of the Oort cloud and the Kuiper Belt. ... The astronomical unit (AU or au or a. ...
Marochnik, Leonid S.; Mukhin, Lev M., Zagdeev, Roald S. (1991). “The Oort Cloud”, Planetary Sciences: American and Soviet Research/Proceedings from the U.S.-U.S.S.R. Workshop on Planetary Sciences, 251.
Clouds form in the troposphere, which is the layer of the atmosphere that is closest to the surface of the Earth.
Altostratus clouds are usually not as dense as stratus clouds so you may be able to see the Sun, which you may not be able to do if you were looking through Stratus clouds.
Cirrus clouds that are layered are called cirrostratus clouds and cirrus clouds that form clumps are called cirrocumulus.
The distinction between a hill and a mountain is unclear and largely subjective, but a hill is generally somewhat lower and less steep than a mountain.
Hills may form through a number of geomorphic phenomena: faulting, erosion of larger landforms, such as mountains and movement and deposition of sediment by glaciers (eg.
Hills have become sites for many famous battles, including the Battle of Bunker Hill (which was actually fought from Breed's Hill) in the American War for Independence and Cemetery Hill and Culp's Hill in the Battle of Gettysburg, the turning point of the American Civil War.
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