A high pressure area is an area where the air sinks. As it does, it warms up by the adiabatic effect of a greater pressure and that causes the clouds to evaporate, giving place to a clear sky
Because of genetic variation
<span>There wasn't many vaccinations back in the day and medicine slowly developed through years passing by. Also eras such as the Black plague and others really helped develop medicines and vaccinations moving forward for people to use.
Hope this helps.</span><span />
