Experiments have shown the importance of temperature, but the trigger event, especially in arid regions, is often a storm.
ɛkspˈɛɹɪmənts hæv ʃˈoʊn ðɪ ɪmpˈoːɹtəns ʌv tˈɛmpɹɪtʃɚ, bˌʌt ðə tɹˈɪɡɚɹ ᵻvˈɛnt, ɪspˈɛʃəli ɪn ˈæɹɪd ɹˈiːdʒənz, ɪz ˈɔfən ɐ stˈoːɹm.