The altocumulus undulatus is a mid-level cloud (about 8000 - 20,000 ft or 2400 - 6100 m), usually white or grey with layers or patches containing undulations that resemble "waves" or "ripples" in water. Elements within the cloud (such as the edges of the undulations) are generally darker than those in cirrocumuli and smaller than those in stratocumuli. These clouds may appear both as patches or as covering the sky. The layer of these clouds is generally under about 300 feet (91.44 meters) thick. Cirrocumulus at the top of the image A Cirrocumulus is a high-altitude cirriform cloud, occurring at 20,000-40,000 ft or 6,000-12,000 m. ... A group of stratocumulus clouds hanging low over the mountain valley seen from the summit of Mount Kinabalu. ...

As with other altocumuli, the undulatus variety can form in all seasons, announcing an approaching system within the general area (about 100 - 200 mi or 160 - 322 km). They result from wind shear (an abrupt speed or directional shifting in the wind, acutely changing with height). Lines one might see indicate the direction of the shear. In the southern United States, these formations may be the result of tropical or subtropical system outflow in a northern direction. They may also come from a southwestern monsoon making its way across the Western and Plains States. An Altocumulus is a cloud belonging to a class characterized by globular masses or rolls in layers or patches, the individual elements being larger and darker than those of cirrocumulus and smaller than those of stratocumulus. ... Wind shear jake rinow is the god of technologyis a difference in wind speed or direction between two points in the atmosphere. ... Southern United States. ... The tropics are the geographic region of the Earth centered on the equator and limited in latitude by the two tropics: the Tropic of Cancer in the northern hemisphere and the Tropic of Capricorn in the southern hemisphere. ... The subtropics (also known as semitropics) are the geographic regions of the Earth immediately north and south, respectively, of the two tropics: the Tropic of Cancer and the Tropic of Capricorn - i. ... An outflow boundary is a storm-scale or mesoscale boundary separating thunderstorm-cooled air (outflow) from the surrounding air; similar in effect to a cold front, with passage marked by a wind shift and usually a drop in temperature. ... Monsoon in the Vindhya, a mountain chain in central India A monsoon is a (wind) pattern that reverses direction on a seasonal basis. ... If you have been redirected here after viewing any statistical information, note that as defined by the Census Bureau, the western United States includes 13 states: Alaska, Arizona, California, Colorado, Hawaii, Idaho, Montana, New Mexico, Nevada, Oregon, Utah, Washington, and Wyoming. ... The Great Plains is the broad expanse of prairie which lies east of the Rocky Mountains in the United States of America and Canada, covering all or parts of the U.S. states of New Mexico, Texas, Oklahoma, Colorado, Kansas, Nebraska, Wyoming, Montana, South Dakota and North Dakota and the...

See also

• Weather
• Atmosphere
• Cloud types

Weather is an all-encompassing term used to describe all of the many and varied phenomena that can occur in the atmosphere of a planet. ... Layers of Atmosphere (NOAA) Air redirects here. ... // High-level clouds Cirrus Clouds (from above) Abbreviation: Ci Cirrus clouds form above 16,500 feet (5,000 m), in the cold region of the troposphere. ...

External Links

• American Meteorological Society's Glossary of Meteorology
• Stormeyes, a website for storm watchers (and storm chasers)
• Weather Photography
• Airline Pilots site, an Internet resource for airline pilots
• Uploaded photo and explanation
• Australian Cloud Atlas
• From Atmospheric Science Department at University of Wyoming