Which of the following conditions is most important in establishing a temperature inversion a layer of cold air over one of warm air two layers of warm air next to each other a layer of warm air over a layer of cold air two layers of warm air one on top of the other

the following condition that is the most important to establish a temperature inversion is a layer of warm air on top of a cold one. A temperature inversion is simply a thin layer of air where instead of having a normal decrease in temperature as one goes higher, it switches and has an increase as you elevate.

So  if  the sum of the enthalpies of the reactants is greater than the products, the  reaction  will be  exothermic.  if  the products side has a larger enthalpy, the  reaction  is  endothermic. you may wonder why  endothermic reactions, which soak up energy or enthalpy from the environment, even happen