Weird Gravity Waves Pulse From a Tropical Cyclone

Last Monday, May 13, the Suomi NPP satellite captured a fascinating image of Tropical Cyclone Mahasen as it moved northeast over the Bay of Bengal. The clouds of the storm itself weren’t optically visible in the darkness of a nearly new Moon, but lightning flashes within it were… as well as the eerie ripples of atmospheric gravity waves spreading outwards from its center.

According to the Space Physics Research Group at the University of California, Berkeley:

Gravity waves are the oscillations of air parcels by the lifting force of bouyancy and the restoring force of gravity. These waves propagate vertically as well as horizontally, and actively transport energy and momentum from the troposphere to the middle and upper atmosphere. Gravity waves are caused by a variety of sources, including the passage of wind across terrestrial landforms, interaction at the velocity shear of the polar jet stream and radiation incident from space. They are found to affect atmospheric tides in the middle atmosphere and terrestrial weather in the lower atmosphere. (Source)

Atmospheric gravity waves aren’t to be confused with gravitational waves in space, which are created by very dense, massive objects (like white dwarf stars or black holes) orbiting each other closely.

When the image was captured, Tropical Cyclone Mahasen was moving north through the Indian Ocean along a track that placed landfall along the Bangladesh coast. As it moved off the coast of India Suomi’s VIIRS Day-Night Band was able to resolve lightning flashes towards the center of the storm, along with mesopheric gravity waves emanating outwards like ripples in a pond.

Such gravity waves are of particular interest to air traffic controllers so assist in identifying areas of turbulence.

Since the moon was in a new phase, the lights and other surface features of India and Sri Lanka are clearly visible although the clouds of Mahasen are not — a tradeoff that occurs as the amount of moonlight cycles throughout the month.

TS Mahasen on May 17, 2013 (Chelys/EOSnap)
TS Mahasen on May 17, 2013 (Chelys/EOSnap)

Over the course of the next few days Mahasen weakened into a deep depression, making landfall as a tropical storm on Bangladesh on May 16. In preparation for the storm large-scale evacuations were recommended for parts of Myanmar; however, this resulted in the overcrowding of boats and several vessels capsized. (Source: eosnap.com)

NASA launched the National Polar-orbiting Operational Environmental Satellite System Preparatory Project (or NPP) on October 28, 2011 from Vandenberg Air Force Base. On Jan. 24, NPP was renamed Suomi National Polar-orbiting Partnership, or Suomi NPP, in honor of the late Verner E. Suomi. It’s the first satellite specifically designed to collect data to improve short-term weather forecasts and increase understanding of long-term climate change.

Suomi NPP orbits Earth about 14 times a day, observing nearly the entire surface of the planet.

Main image source: NASA Goddard Space Flight Center

An Enormous Arctic Spiral

Looking south across the southern tip of Greenland, this satellite image shows an enormous cloud vortex spiraling over the northern Atlantic ocean on January 26, 2013. An example of the powerful convection currents in the upper latitudes, these polar low cyclones are created when the motion of cold air is energized by the warmer ocean water beneath.

Sometimes referred to as Arctic cyclones, these spiraling storms can bring gale-force winds and heavy snowfall over a wide area of ocean during their 12- to 36-hour lifespans. Hurricane-type storms don’t only form in the tropics!

This image was captured by the MODIS instrument on NASA’s Aqua satellite from its polar orbit 705 km (438 miles) above the Earth. The view has been rotated so south is up; the southernmost tip of Greenland can be seen at lower right. Click for an impressive high-resolution view.

Image via EOSNAP/Chelys