The spelling of the word "Rubicel" is based on its phonetic transcription. According to the International Phonetic Alphabet (IPA), "Rubicel" is pronounced as /ruːbɪsɛl/. The IPA phonetic symbols show us the exact pronunciation of every sound in the word. The "u" represents the long "oo" sound, while "i" and "e" are pronounced as short vowels. The "c" is pronounced as "s" and "l" is pronounced at the end, which is a silent letter. Therefore, the spelling of "Rubicel" accurately reflects its pronunciation, following the rules of the IPA phonetic alphabet.