Shapes from wind blowing long grass

Does anyone know the word for shapes caused by wind blowing long grass, where light and dark appear to move across the field?

I'd like to say "He watched the _____ move across the field in the wind."

[Image from Chris Hawking via YouTube. Click to play the video.]

Solution 1:

He watched the waves move across the field in the wind.

Have a look at more grass waves videos on google.

Longitudinal waves
In longitudinal waves, the oscillations are along the same direction as the direction of travel and energy transfer. Sound waves and waves in a stretched spring are longitudinal waves. P waves (relatively fast moving longitudinal seismic waves that travel through liquids and solids) are also longitudinal waves. Longitudinal waves show area of compression and rarefaction. http://www.bbc.co.uk/schools/gcsebitesize/science/aqa/waves/generalwavesrev2.shtml

Solution 2:

The first verse of the American patriotic song "America, the Beautiful" makes reference to exactly this phenomenon in a very poetic way:

Oh beautiful for spacious skies;
For amber waves of grain;
For purple mountain majesties;
Above the fruited plain!
...

It refers to the wind blowing through wheat fields, so waves is a perfectly apt description.

Solution 3:

Ripples, perhaps?

ripple noun [ C ]

a small wave on the surface of water:

• The stone she threw caused ripples to spread across the lake.

Cambridge Dictionary

I would say that the term doesn't just apply to water.