Halos

Written by Alice Gabriel on Monday, 18 November 2013. Posted in Cruise 2013

16 November 2013, Alice Gabriel

Halos

 

Leaving Le Port into the flat seas surrounding Reunion we were stunned by a colourful circle surrounding the sun in the otherwise blue sky. The ring, surrounding the shallow sun at a distance of 22 degrees, is the most common of more than 50 known 'Halo' effects. These originate from sunlight scattering off ice crystals, stemming for example from Cirrus clouds at great heights.

The sailor's proverb ‘a Halo foretells bad weather’, came true as we did indeed experience storms in the following days. Gusts of wind, rain, thunder and up to 3 metre swell plus 2 metre wind sea accompanied us on our way South-West. That which is bad news for the newcomers (and their stomachs) is good news for the on-board weather observatory: finally an interesting weather situation beyond 'boring' high pressure cells! In the coming days we can watch registering balloons rising up to heights more than 20 km, measuring temperature, air humidity and pressure and transmitting data via radio and satellite directly into German Weather Service network.

Thus, not only we can prepare for the weather and ocean conditions awaiting us, but our cruise also contributes to global weather observations enabling, for example, ecological friendly fuel optimized air routes.

About the Author

Alice Gabriel

Alice Gabriel

PostDoc at the Department of Earth Sciences (Geophysics) of the Ludwig-Maximilians-Universität München. Interested in earthquake dynamics, wave propagation and strong ground motions as well as fundamental earthquake physics.


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