Transverse instability of megaripples

Mar 20, 2012

Aeolian ripples, which form regular patterns on sand beaches and desert floors, indicate the fundamental instability of flat sand surfaces under the wind-induced transport of sand grains.

Two kinds of sand ripples exist: normal, small ripples and megaripples with wavelengths reaching up to several meters. They differ also in their grain-size distributions (unimodal for sand ripples and bimodal for megaripples).

While sand ripples form almost straight lines, megaripples have greater sinuosity due to their transverse instability, a property that causes small megaripple undulations to grow with time.

The origin of the instability is due to variations in megaripple height, which do not diminish over time, as well as to the inverse dependence of ripple drift velocity on height. Thus, the taller regions of ripples will move more slowly than the adjacent, shorter portions, an outcome that promotes further perturbation growth.

Hezi Yizhaq of Ben-Gurion University of the Negev and colleagues provide an example, based on field work, of the transverse instability of megaripples. The instability growth rate depends on the difference between the heights of the different segments of the megaripple.

Their results suggest a for the transverse instability of megaripples and new insight into the spatial patterns of .

Explore further: TRMM satellite sees Tropical Storm Phanfone fragmented

More information: Hezi Yizhaq et al., Geology, Posted online 19 Mar. 2012; doi: 10.1130/G32995.1

Journal reference: Geology search and more info website

Provided by Geological Society of America

5 /5 (1 vote)
add to favorites email to friend print save as pdf

Related Stories

Scientists explore the physics of bumpy roads

Jul 07, 2009

sand or gravel or snow -- develops ripples that make driving a very shaky experience. A team of physicists from Canada, France and the United Kingdom have recreated this "washboard" phenomenon in the lab with ...

Mars Dunes: On the Move?

Mar 04, 2010

(PhysOrg.com) -- New studies of ripples and dunes shaped by the winds on Mars testify to variability on that planet, identifying at least one place where ripples are actively migrating and another where the ...

First images of flowing nano ripples

Mar 21, 2006

Delft University of Technology (Holland) researchers have shed new light on the formation of nanoscale surface features, such as nano ripples. These features are important because they could be useful as templates ...

Image: Blue on Mars

Feb 17, 2011

This image shows part of the floor of Rabe Crater, a large impact crater in Mars' southern highlands.

Recommended for you

NASA's HS3 looks Hurricane Edouard in the eye

2 hours ago

NASA and NOAA scientists participating in NASA's Hurricane and Severe Storms Sentinel (HS3) mission used their expert skills, combined with a bit of serendipity on Sept. 17, 2014, to guide the remotely piloted ...

Tropical Storm Rachel dwarfed by developing system 90E

7 hours ago

Tropical Storm Rachel is spinning down west of Mexico's Baja California, and another tropical low pressure area developing off the coast of southwestern Mexico dwarfs the tropical storm. NOAA's GOES-West ...

NASA ocean data shows 'climate dance' of plankton

10 hours ago

The greens and blues of the ocean color from NASA satellite data have provided new insights into how climate and ecosystem processes affect the growth cycles of phytoplankton—microscopic aquatic plants ...

Glaciers in the grand canyon of Mars?

12 hours ago

For decades, planetary geologists have speculated that glaciers might once have crept through Valles Marineris, the 2000-mile-long chasm that constitutes the Grand Canyon of Mars. Using satellite images, ...

NASA support key to glacier mapping efforts

12 hours ago

Thanks in part to support from NASA and the National Science Foundation, scientists have produced the first-ever detailed maps of bedrock beneath glaciers in Greenland and Antarctica. This new data will help ...

User comments : 0