Questions with the keyword 'crystal'

• How are circumzenithal arcs formed (they look like upside-down rainbows)? I actually saw one once, and I know it is to by doppler to Adam, SheilaCategory: General Comments: (so far, 3s comments )
• If salt is made up of alternating positive and negative ions, why don’t the crystals of salt in a salt shaker all by freddie to Adam, Geoff, Rob, Sheila, SuzieCategory: General Comments: (so far, 11s comments )