Class A (type D) CpG ODNs (CpG-A ODNs) contain a central palindromic phosphodiester (PO) CpG sequence and a PS-modified 3â poly-G tail. The poly G tails form intermolecular tetrads that result in high molecular weight ordered structures.
Why does a tornado form when cold and hot air meet? The collision of warm and cold air is not the direct cause of a tornado, nor is it absolutely necessary. When a cold air mass pushes into a warm air mass (this is called a câ¦old front) the warmer, less dense air is forced upwards.
They are similar to the normal tornadoes, of vertically rotating column of air. But they occur under clean skies and are very weak. They form when a strong hot updraft is formed near the ground on a hot day. A Dust-Devil tornado occurs when the sun heats dry land surfaces forming a twisting column of air.