In this instance the word embryo is used to describe the developmental stage of a thundercloud. However, the word embryo is typically used to refer to the early developmental stage of a creature.
"A group of cumulus developing into a possible thunderstorm, March 11, 2009" by Bazar del Bizzarro is licensed under CC BY.
A01 The Blessing Way (01-07) p. 57
Encyclopædia Britannica Online N.d. embryo. http://www.britannica.com/EBchecked/topic/185610/embryo, accessed September 24, 2014.
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