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.
The spring also produces the most tornadoes, with an average of 35 tornadoes each year. Summer. Summer, June through August, is the hottest time of the year with a mean temperature of 24 Â°C (75 Â°F) and a mean precipitation of 300 mm (12 inches) with June having more precipitation than either July or August.