The spelling of the word "black heat" is straightforward when using IPA (International Phonetic Alphabet) phonetic transcription. The first word "black" is spelled as /blæk/, with the "a" pronounced as the short "a" sound. The second word, "heat," is spelled as /hiːt/, with the "ea" pronounced as a long "e" sound. Together, "black heat" is pronounced as /blæk hiːt/, with emphasis on the second syllable of "heat." This term refers to extreme temperatures and is commonly used in industrial settings.