Earthquake data provided courtesy University of Utah. Yellowstone is one of the most seismically active areas in the United States. Approximately 1,000 to 3,000 earthquakes occur each year in the Yellowstone area; most are not felt. They result from the enormous number of faults associated with the volcano.
What are the effects of environmental pressure on natural selection? A: Environmental pressure is another term for natural selection, a process that encourages some genes to survive because they are conducive to the environment while others die. This process slowly causes a distinct species to evolve over time. Continue Reading.
By definition, atmospheric or air pressure is the force per unit of area exerted on the Earthâs surface by the weight of the air above the surface. The force exerted by an air mass is created by the molecules that make it up and their size, motion, and number present in the air. 1  These are important factors because they determine the temperature and density of the air and thus its pressure. The number of air molecules above a surface determines air pressure. As the number of molecules increases, they exert more pressure on a surface and the total atmospheric pressure increases. By contrast, if the number of molecules decreases, so too does the air pressure. Today, air pressure is often measured with a mercury or aneroid barometer. A mercury barometer measures the height of a mercury column in a vertical glass tube.