Emphasis Preaching Journal

As on a torrid summer day, when out of nowhere one of those elusive whirlwinds suddenly appears and tosses around pieces of straw and dust, so it was that the suddenness of the Spirit's appearing was described as a whirlwind or its big cousin the tornado (as Archibald Robertson in his commentaries). Even though the apostles had been expecting the coming of the Spirit, as promised, and had stayed in the city of Jerusalem until this should transpire, they were no less surprised and overwhelmed.