Halo Around the Sun: caused by ice crystals, but what if it's too warm for ice?

Question

There was a halo around the sun today.

(see pics: http://images.aad.gov.au/img.py/198d.jpg )

As today was the first day of summer, and a nice 75 degrees or so, it seems too warm for the "ice crystal" theory.

I live on the 45th parallel.

So, could someone explain how this phenomena works?

Thank you!

Answer 1

Please see the following link to better understand

Answer 2

The upper atmosphere is really cold, even in the tropics. A jet flies at about 40,000 feet, outside air is about -55 C. If there is any moisture there it will form ice crystals. The suns light then reflects off the crystals forming the halo that you can see.

Here is a chart of approximate tempteratures at different altitudes

Sea level 0 m 0 ft 15 C 59 F

100 m 300 ft 15 C 59 F

1500 m 5000 ft 5 C 41 F

3000 m 10000 ft -5 C 23 F

5000 m 18000 ft -20 C -4 F

9000 m 30000 ft -45 C -49 F

12000 m 40000 ft -55 C -67 F

16000 m 53000 ft -56 C -69 F