Gravity waves: “Undular bores” race across Lake Superior

We're getting some amazing imagery from NOAA's GOES-16 satellite. Check out the impressive "undular bores" that raced across Lake Superior Monday.

Undular bores are created when air masses of different density collide. Like a rock thrown into a pond, the waves propagate outward. Undular bores also occur in advance of cold-air outflows (gust fronts) from thunderstorms.

Here's a good description from the Wikipedia post.

In meteorology, an undular bore is a wave disturbance in the Earth's atmosphere and can be seen through unique cloud formations. They normally occur within an area of the atmosphere which is stable in the low levels after an outflow boundary or a cold front moves through.

Undular bores are usually formed when two air masses of different temperatures collide. When a low level boundary such as a cold front or outflow boundary approaches a layer of cold, stable air, it creates a disturbance in the atmosphere producing a wave-like motion, known as a gravity wave. Although the undular bore waves appear as bands of clouds across the sky, they are transverse waves, and are propelled by the transfer of energy from an oncoming storm and are shaped by gravity. The ripple like appearance of this wave is described as the disturbance in the water when a pebble is dropped into a pond or when a moving boat creates waves in the surrounding water. The object displaces the water or medium the wave is travelling through and the medium moves in an upward motion. However, because of gravity, the water or medium is pulled back down and the repetition of this cycle creates the transverse wave motion.[1]

NOAA's GOES 16 continues to amaze in the great detail. Highly detailed images like this tornadic outbreak in Iowa show the value of this platform.

As observing systems improve, our ability to understand and visualize micro-scale atmospheric phenomenon grows.

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