# Mega ripples have a mathematical pattern capable of “predicting” their behavior

Mega ripples appear to have a mathematical pattern capable of providing clues about a planet’s atmospheric conditions. An international study, led by Leipzig University, believes that the discovery could improve the ability to assess remote climate events from these sediments.

In order for dunes to form, all that is needed is sand on the surface of a planet and, of course, an atmosphere to produce the wind that shapes this landscape. Sand waves ranging from 30 cm to several meters in height are known as mega ripples, structures observed on both Earth and Mars.

It has long been known that the sizes of the grains involved in these ripples influence their shapes, which are never the same — much less the winds that push them. Now, the new study has uncovered a mathematical pattern to the mega ripples.

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When dividing the size of the coarser grains by the diameter of the finer ones, the result is always a similar number. The researchers believe that this number can be used to categorize different sand formations and the specific processes of grain transport — wind.

## Relationship of the winds with the grains of sand

The varying sizes of sand grains are carried by the winds at different speeds. The result of this is mega-undulations, where the largest grains accumulate at the tops of the dunes, while the smallest are deposited in the depressions between them.

For the study, the team analyzed mega-swells from Israel, China, Namibia, India, Israel, Jordan, Antarctica and New Mexico. In addition, they added data from observations made in the dunes on Mars and carried out in a wind tube in the laboratory.

The results showed that mega-swells are more vulnerable to wind changes than small dunes. For example, if the winds get stronger, it is the mechanism responsible for these structures that becomes predominant in the landscape.

For the researchers, these calculations can be applied both to predict the formation of these sand structures and to assess atmospheric conditions from a remote time based on the sediments of mega-swells. In other words: it’s like reading a planet’s atmosphere through this sandy formation.

Theoretical physicist Katharina Tholen, lead author of the study, said that if it were possible to use prevailing atmospheric conditions to explain the formation and migration of sand waves on Earth and other planets, it would be an important step towards understanding the present climate and past.

The study was presented in the journal Nature Communications.