The word "luche" is spelled with an "h" after the "c" because the "ch" sound in the word is a voiceless palatal fricative. In IPA phonetic transcription, it is represented by the symbol /ç/. The letter "c" on its own represents a voiceless velar stop, as in the word "cat". By adding the "h", we indicate that the "c" is producing a different sound. This is similar to how the "g" in "gift" produces a different sound than the "g" in "goat".