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.
Rating Newest Oldest. Best Answer: Yes, they very well do. Tornadoes need warm, moist air to form and intensify, and most people believe that this type of air is not possible during nighttime hours. But it is. The surface cools slower than the air, and the Sun's heat could still be on the surface.