AbeShrek

I'm recalling an article in Scientific American some decades ago addressing the Green Flash mystery of being frequently observed by eyes but never captured on film - its a biological phenomenon produced by prolonged staring into the sun as it nearly disappears beyond the horizon. The light reaching the eyes is mostly red due to atmospheric refraction and causes saturation and reduces sensitivity of red-sensitive segments of photoreceptor cones in the retina. As the intensity drops quickly the desensitized red-receiver portions will produce a lower relative neural response receivers for other color , thus altering the neural color balance and creating a perception of green color. This may be similar to the momentary blindness we experience when entering from a brightly-lit room into a dimly lit one - except that it has a bias for red color illumination. Another possible mechanism hinted at in Wikipedia is light frequency doubling that occurs in the retina from invisible incident solar radiance at near-infrared wavelengths of, say 1.06 microns, due interaction with the nonlinear response of the retinal photoreceptors, resulting in wavelengths of 0.53 microns, smack in the visible green band. That invisible radiance penetrates through the atmosphere (if clear) and propagates through the eye to the retina but our photoreceptors are insensitive to it - however they will react to a frequency-doubling effect locally converting it to green light.

I'm recalling an article in Scientific American some decades ago addressing the Green Flash mystery of being frequently observed by eyes but never captured on film - it has to do with saturating the red-sensitive portions of the photoreceptor cones in retina by prolonged staring into the sun as it nearly disappears beyond the horizon. The light reaching the eyes at that point is strongly red due to refraction in the atmosphere, and the intensity drops quickly - and at some point when the photoreceptors come out of saturation the neural backlash creates a perception of green color. Another possible mechanism is hinted at in Wikipedia is frequency doubling in the retina from invisible incident solar light at near-infrared wavelengths of, say 1.06 microns, due interaction with the nonlinear response of the retinal photoreceptors, resulting in wavelengths of 0.53 microns, smack in the visible green band. That invisible radiance penetrates through the atmosphere (if clear) and propagates through the eye to the retina but the photoreceptors are insensitive to it - but will react if there's a frequency doubling effect locally producing green light.

Hi Ken! Were you able to spot the Green Flash during your sunsets at sea? I've been told it's best seen if the horizon is clear of clouds.

Ken... really great pix, thanks! Now, with your having all these fresh-but-brief impressions, should you have a future chance to revisit Dubai on-land, perhaps on a stopover, for how long would you plan a stay there? What would be the must-sees?

Hello Ken! Thanks for the detailed coverage! At this point, did you arrange for any visas in advance for any of your ports of call? Do you know how many will be aboard for the next leg?