Siera or Sierra: How To spell?
The word Siera is misspelled against Sierra, a noun meaning "A ridge of mountain and craggy rocks, with a serrated or irregular outline; as, the Sierra Nevada."
Sierra has double "rr" is mispronounced as "r"Remember double 'RR' in between the strings sie & a which should not be misspelled with single 'R'
Wrong Spelling:  sie-r-a  Correct Spelling:  sie-rr-a 
Find more wrongly spelled words of Sierra to spell it well.