FDC-couch

today

8:30 a.m. Audubon Society Field Trip See Event Description

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9 a.m. Arcata Farmers' Market Arcata Plaza

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9:30 a.m. Discovery Walk: Unknown Waterfront See Event Description

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9:30 a.m. Manila Dunes Restoration Manila Community Center

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10 a.m. Manila Dunes Guided Walk Manila Community Center

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10 a.m. Library Book Sale Humboldt County Library

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10 a.m. Dia de los Muertos and Mexican Folk Art Sale Private Eureka home

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10 a.m. Final Arcata Farmer's Market Arcata Farmers' Market (off the plaza)

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11 a.m. Donlin Foreman Dance Workshop Dell'Arte

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2 p.m. Humboldt Coastal Nature Center Draft Trails Plan Walk Stamps House

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5 p.m. Bati Zado and Show Redwood Raks World Dance Studio

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6 p.m. The Tumbleweeds Chapala Cafe

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6 p.m. Ali Chaudhary (jazz duo) Libation

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6:30 p.m. Not Evil, Just Wrong Humboldt Area Foundation

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7 p.m. Guitar Stan (country) Old Town Coffee & Chocolates

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8 p.m. Guitar Orchestra of Barcelona Arkley Center for the Performing Arts

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8 p.m. Stones in His Pockets Arcata Playhouse

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8 p.m. A Christmas Carol North Coast Repertory Theater

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8 p.m. Donna Landry Swing Dance Moose Lodge

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8 p.m. North Coast Wind Ensemble Fulkerson Recital Hall at HSU

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8:30 p.m. The Last Minute Men (international) Cafe Mokka

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9 p.m. Ian McFeron Band (folk rock) Six Rivers Brewery

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9 p.m. The Michael Paul Band WAVE @ blue lake casino

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9 p.m. The Generatorz (classic rock) Central Station Cocktail Lounge

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9 p.m. Taxi Bear River Casino

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9 p.m. VJ Itchie Fingaz Pearl Lounge

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9 p.m. Jack Ruby Presents + Blue Street + Acufunkture (DIY rock) Jambalaya

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9 p.m. 2nd Annual Scorpio Bash The Red Fox Tavern

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10 p.m. Music by DJ Sidelines

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10 p.m. DJ Icy Hot Aunty Mo's Lounge

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10 p.m. Jemimah Puddleduck (rock) Humboldt Brews

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10 p.m. White Manna + Midday Veil + The King Salmon Duo (rock) Jambalaya

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11 p.m. Radio Moscow (psychadelic blues) + Mosquito Bandito (one-man surf/garage) The Alibi Lounge and Restaurant

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previous columns

March 6, 2008

The Ins and Outs of Tides

The Moon's gravity decreases with distance, so it pulls unequally ...

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Feb. 21, 2008

More Power to You

PG&E is planning an upgrade of its aging Humboldt Bay ...

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  • NASA wake vortex study at Wallops Islands NASA Langley Research Center, May, 1990 NASA wake vortex study at Wallops Islands NASA Langley Research Center, May, 1990
  • Diagram showing tip vortex, by Don Garlick. Diagram showing tip vortex, by Don Garlick.
  • Diagram showing tip vorteces, by Don Garlick Diagram showing tip vorteces, by Don Garlick
  • Diagram of tip separation to wing span of pink footed geese, by Don Garlick Diagram of tip separation to wing span of pink footed geese, by Don Garlick
  • Graph of drag % relative to solo flight, by Don Garlick. Graph of drag % relative to solo flight, by Don Garlick.
In Formation

In Formation

By Don Garlick

The V-formations of honking Aleutian Cackling Geese that decorate our skies pose the question as to whether they fly in formation for social cohesion or to conserve energy. The reason military jets fly in V-formation is not to conserve energy, but to permit trailing pilots to remain in visual contact with the leading pilot. Fortunately, there are methods by which the question of energy conservation can be investigated. If trailing birds benefit from air currents produced by leading birds, then their relative positions should optimize those effects.

One might expect that a bird following very closely, with beak on tail, would experience less drag. Cyclists employ that "drafting" technique on the race track. However, air immediately behind a leading bird is sinking, so drafting is not a good tactic in flight.

Theoretical calculations indicate that a bird in a large formation could reduce "induced air drag" by 60 percent by riding the rising half of the wing-tip vortex produced by the bird ahead. The optimum effect occurs when wing tip directly follows wing tip with zero lateral spacing. Examination of vertically-taken photos of pink-footed geese confirm that those geese fly close to that optimal geometry.

The telemetered heart rate of a pelican has been found to be faster while flying solo than in formation (Nature, Oct. 18, 2001). This further confirms the energy-saving hypothesis. And a heavy goose flying non-stop from Humboldt to Alaska needs to be as energy-efficient as possible. That is why our sky is festooned with geese in formation.

Thirty years ago there existed fewer than 800 Aleutian Geese. Thanks to the removal of introduced foxes from critical nesting islands, their population now exceeds 100,000. That's too many, according to local dairymen who see their pastures flying away.

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