DIVE DRY WITH DR. BILL #752: THE GREEN FLUSH
Many of my readers have undoubtedly heard about, or even seen, the green flash that occurs at sunset. I have witnessed it several times, usually while out on dive boats or on oceanic islands around the world. It is caused by refraction of the sun's light which separates out the different colors of the solar spectrum. Blue light is refracted the most, but much of it gets scattered before it reaches the observer. What remains appears green when it reaches our eyes.
During my early years on the island (1969-79) I lived out at Toyon Bay where I taught science and math at the Catalina Island School. It was a different world from life in Avalon! The school's toilets back in those daze were fresh water and behaved pretty much as the ones in my home town of Chicago did. When I moved into Avalon, one of the changes I soon noticed was that toilets here were fed by salt water. It figures. Back in Chicago we had a near-endless supply of fresh water from Lake Michigan and here on Catalina an endless supply of salt water from the Pacific Ocean!
Now when I wake up in the middle of the night and need to make a trip to the toilet, I often leave the lights off to better ensure I'll fall back to sleep. Fortunately my aim is good even in the dark. Not long after I settled into my first apartment here, I had an evening of "enlightenment." As I flushed the john, I saw a wondrous glow coming from it. Yes, the "green flush."
What do I mean by this? Let me explain. As a child back in Chicago, I thought I'd become an entomologist like my three uncles. Yes, a terrestrial "bug" collector! One of the insects I enjoyed collecting was the firefly. Most of you are aware that fireflies emit light using bioluminescence. This involves a chemical reaction that produces visible light. An organic substance known as luciferin is oxidized by an enzyme known as luciferase. There are many different variations of this in a wide range of critters.
During my high school years I began to transition from land-based "bugs" to the marine world. At Harvard that metamorphosis was complete, perhaps due to all the cockroach dissections I had to do during Professor Frank Carpenter's entomology class. I quickly returned to my marine biological mentor, Dr. Barry Fell. The only "bugs" I dealt with after that were more commonly known as lobster!
A multitude of marine organisms utilize similar bioluminescence pathways like the fireflies. Heck, in the depths of the ocean, it may be the only form of light they see! There are fish, crustaceans, comb jellies, jellyfish and cephalopods that emit their own light. However, most of us never see these deep sea creatures. Fortunately for us there are also microscopic organisms such as dinoflagellates that live closer to the surface and may emit large clouds of light when waves crash on the beach.
Now these same dinoflagellates are sucked up by the city and deposited in our toilet bowl reservoirs. When we flush the toilet, the turbulence in the water causes them to glow. In dinoflagellates that have been well studied, the peak frequency of light emission is at 475 nm which puts it at the boundary between blue and cyan, so you could call it the blue-green flush but what fun is that?
Now you don't have to visit the toilet at night to see this. Those brave souls that skinny dip or SCUBA dive in our waters at night can occasionally see the dinoflagellates glow as they move through the water. I can think of several night dives when I've seen a long blue-green streak in the water and thought it might be a (gulp) great white shark. Fortunately, it was usually a sea lion streaking through the water. Hmmm... experiencing the green flush may be safer.
© 2017 Dr. Bill Bushing. For the entire archived set of over 700 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Firefly (courtesy of Art Farmer) and dinoflagellates from our waters; bioluminescent dinoflagellates triggered by waves breaking (courtesy of Phil Hart) and the safest place to view the green flush!
Many of my readers have undoubtedly heard about, or even seen, the green flash that occurs at sunset. I have witnessed it several times, usually while out on dive boats or on oceanic islands around the world. It is caused by refraction of the sun's light which separates out the different colors of the solar spectrum. Blue light is refracted the most, but much of it gets scattered before it reaches the observer. What remains appears green when it reaches our eyes.
During my early years on the island (1969-79) I lived out at Toyon Bay where I taught science and math at the Catalina Island School. It was a different world from life in Avalon! The school's toilets back in those daze were fresh water and behaved pretty much as the ones in my home town of Chicago did. When I moved into Avalon, one of the changes I soon noticed was that toilets here were fed by salt water. It figures. Back in Chicago we had a near-endless supply of fresh water from Lake Michigan and here on Catalina an endless supply of salt water from the Pacific Ocean!
Now when I wake up in the middle of the night and need to make a trip to the toilet, I often leave the lights off to better ensure I'll fall back to sleep. Fortunately my aim is good even in the dark. Not long after I settled into my first apartment here, I had an evening of "enlightenment." As I flushed the john, I saw a wondrous glow coming from it. Yes, the "green flush."
What do I mean by this? Let me explain. As a child back in Chicago, I thought I'd become an entomologist like my three uncles. Yes, a terrestrial "bug" collector! One of the insects I enjoyed collecting was the firefly. Most of you are aware that fireflies emit light using bioluminescence. This involves a chemical reaction that produces visible light. An organic substance known as luciferin is oxidized by an enzyme known as luciferase. There are many different variations of this in a wide range of critters.
During my high school years I began to transition from land-based "bugs" to the marine world. At Harvard that metamorphosis was complete, perhaps due to all the cockroach dissections I had to do during Professor Frank Carpenter's entomology class. I quickly returned to my marine biological mentor, Dr. Barry Fell. The only "bugs" I dealt with after that were more commonly known as lobster!
A multitude of marine organisms utilize similar bioluminescence pathways like the fireflies. Heck, in the depths of the ocean, it may be the only form of light they see! There are fish, crustaceans, comb jellies, jellyfish and cephalopods that emit their own light. However, most of us never see these deep sea creatures. Fortunately for us there are also microscopic organisms such as dinoflagellates that live closer to the surface and may emit large clouds of light when waves crash on the beach.
Now these same dinoflagellates are sucked up by the city and deposited in our toilet bowl reservoirs. When we flush the toilet, the turbulence in the water causes them to glow. In dinoflagellates that have been well studied, the peak frequency of light emission is at 475 nm which puts it at the boundary between blue and cyan, so you could call it the blue-green flush but what fun is that?
Now you don't have to visit the toilet at night to see this. Those brave souls that skinny dip or SCUBA dive in our waters at night can occasionally see the dinoflagellates glow as they move through the water. I can think of several night dives when I've seen a long blue-green streak in the water and thought it might be a (gulp) great white shark. Fortunately, it was usually a sea lion streaking through the water. Hmmm... experiencing the green flush may be safer.
© 2017 Dr. Bill Bushing. For the entire archived set of over 700 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Firefly (courtesy of Art Farmer) and dinoflagellates from our waters; bioluminescent dinoflagellates triggered by waves breaking (courtesy of Phil Hart) and the safest place to view the green flush!
