Green Flash

Green Flash on the western horizon of Madagascar

A green Flash occurs during a sunset (or sunrise), and i knew that they occurred off of the cost on the Kona side of the island. So i was wondering what causes them? and how can I find the right conditions to see one?

Green Flash off the coast of Hawaii

Causes of the Flash
The green flash is caused from the sun's light being bent in the atmosphere, (this also causes the sky to appear blue) only in the few seconds of maximum length between you and the sun as its mostly beyond the horizon causes the spectrum to be bent in a green hue (usually, it can also appear to be blue, yellow, and even violet) for anywhere from half a second to up to 15 seconds, which is why it's described as a flash.

Seeing the Flash has a few rules

1. Your apparent horizon must be lower than your eye level (which is why the ocean is the perfect requirement although not necessary)
2. The Air MUST be reasonably clean. If there is too much dust, smog, or haze than the light from the sun wont refract properly and you will just see a normal sunset.
3. Because the flash is quite small, (especially if you have never seen it before) some kind of aid will be necessary, such as binoculars, zoom camera lens, opera glasses, etc. But Remember: if the sun isn't comfortable to look at DON'T! you will hurt your eyes. so sunglasses are also a good idea, and they really don't diminish your chances of seeing it.

Sources:

Intro To Green Flashes

Wikipedia

Species Status Clasification

I am wondering, what classifies a species as endangered, threatened, vulnerable, or invasive? Quite a few of us have used these words in our Blogs before and i was wondering what makes that species what it is.

Wikipedia Says that species that have dwindling numbers are divided into 3 categories

• Critically Endangered (CR)-Extremely high Risk of Becoming Extinct (example. Florida panther, only occupies 5% of original range and only has 70 animals left capable of breeding)
  
  
• Endangered (EN)-A Species that is in danger of becoming extinct due to a range of reasons being: over hunting (from other animals and humans), changing environment, loss of environment, or just way to few numbers. (example. Nene which is suffering low numbers and loss of environment)
  
  
• Vulnerable (VU)-A species who's runs a risk of becoming extinct but has not been qualified as an endangered species because numbers may still be high despite other factors like loss of habitat. (example. Polar Bear which still has decent numbers but is loosing habitat to global warming)
  

• Invasive Species- a species that has been introduced to a non-native environment and has become harmful to the native environment and/or human health. (example. Coqui Frog which spreads fast due to high reproduction rate, and is hard to get rid of)