Coriolis - Blog Posts
We’re back in 2019 with an episode that would have been more appropriate to release during hurricane season: a discussion of the Coriolis force! This force was observed centuries ago but takes its name from the scientist who first considered it in terms of theory and physics. It has an impact on a vast range of natural phenomena, from weather patterns to ocean waves to the flights of flies and moths.
Below the cut are the glossary, transcript, a timeline of the people I mention, sources, and music credits. Send me any topic suggestions via Tumblr message (you don’t need an account to do this, just submit as anonymous). You can also tweet at me on Twitter at @HDandtheVoid, or you can ask me to my face if you know me in real life. Subscribe on iTunes to get the new episodes of my so-far-monthly-updated podcast, and please please please rate and review it. Go ahead and tell friends if you think they’d like to hear it, too!
(My thoughts on the next episode are Stephen Hawking, Hedy Lamarr, or famous comets. The next episode will go up in late February.)
Glossary
Coriolis force - a force in a rotating system that acts perpendicular to the direction of motion and to the axis of rotation. On Earth, this tends to deflect moving objects to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.
Ekman transport - the net motion of fluid that results from the balance between Coriolis and turbulent drag forces.
Eötvös effect - the change in perceived gravitational force that results from eastbound or westbound movement on Earth’s surface.
Kelvin waves - an ocean wave that is trapped at the Earth’s equator and along vertical boundaries like coastlines. They move towards the equator when they have a western boundary; towards the poles when they have an eastern boundary; and make a whirlpool when they have a closed boundary, moving counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.
Lagrange points - five points where three bodies can orbit each other, yet stay in the same position relative to each other in a stable configuration. L1-L3 are in line with each other, while L4 and L5 are at the points of equilateral triangles in the configuration.
prograde - when a planet spins from east to west.
Rossby number - used to determine the relative importance of the centrifugal and Coriolis forces in maps of weather patterns. A small Rossby number indicates that a weather system is strongly affected by Coriolis forces, while a large Rossby number signifies that a system is affected by inertial and centrifugal forces.
Transcript
Timeline
Giovanni Battista Riccioli, Italian (1598-1671)
Francesco Maria Grimaldi, Italian (1618-63)
Joseph-Louis Lagrange, French (1736-1813)
Gaspard-Gustave de Coriolis, French (1792-1843)
Sir William Thompson, AKA Lord Kelvin, Scots-Irish (1824-1907)
Baron Loránd Eötvös de Vásárosnamény, Hungarian (1848-1919)
Ottokar Tumlirz, Austrian (1856-1928)
Fridtjof Nansen, Norwegian (1861-1930)
Vagn Walfrid Ekman, Swedish (1874-1954)
Carl-Gustaf Arvid Rossby, Swedish-born American (1898-1957)
Sources
Coriolis Effect via the University of Oregon
Coriolis Force via Wikipedia
Coriolis effect, two centuries before Coriolis via Physics Today (Aug 2011)
Gaspard-Gustave de Coriolis via Wikipedia
Coriolis effect via National Geographic
Hurricane, cyclone, typhoon, tornado – what’s the difference? via African Reporter (Sep 2017)
Wang, B. Kelvin Waves. University of Hawaii: Honolulu, 2002.
Ocean in Motion: Ekman Transport Background via NASA
Ekman transport via Wikipedia
What is a Geodesist? via Environmental Science
“The Second Coming” by W. B. Yeats via Poetry Foundation
Intro Music: ‘Better Times Will Come’ by No Luck Club off their album Prosperity
Filler Music: ‘Ambergris’ by Tipper off their EP Fathoms
Outro Music: ‘Fields of Russia’ by Mutefish off their album On Draught