<span>The answer is synthesis. This is a kind of reaction in which numerous reactants mix to make a single product. Synthesis responses discharge energy in the way of heat and light, so they are exothermic. An instance of a synthesis reaction is the creation of water from hydrogen and oxygen.</span>
When water vapor in the atmosphere loses heat and cools down, condensation happens. As the water vapor cools down and condenses, it attaches to small particles of dust floating in the atmosphere, forming tiny liquid water droplets.