Vowel the vowel sounds of "flower", , form a triphthong or disyllable, depending on dialect. In phonology, diphthongs and triphthongs are distinguished from sequences of monophthongs by whether the vowel sound may be analyzed into different phonemes or not. For example, the vowel sounds in a two-syllable pronunciation of the word "flower" () phonetically form a disyllabic triphthong, but are phonologically a sequence of a diphthong (represented by the letters ) and a monophthong (represented by the letters ). Some linguists use the terms "diphthong" and "triphthong" only in this phonemic sense. The name "vowel" is often used for the symbols
Types of volcanic eruptions propels it forward. Phreatomagmatic eruptions are another type of volcanic eruption, driven by the compression of gas within magma, the direct opposite of the process powering magmatic activity. The third eruptive type is the phreatic eruption, which is driven by the superheating of steam via contact with magma; these eruptive types often exhibit no magmatic release, instead causing the granulation of existing rock. Within these wide-defining eruptive types are several subtypes. The weakest are Hawaiian and submarine, then Strombolian, followed by Vulcanian and Surtseyan. The stronger eruptive types are Pelean eruptions, followed by Plinian eruptions; the strongest eruptions are called