Weather App

" A major aspect of weather interpretation involves being able to understand the actions caused by differences in air pressure. High pressure implies dry weather and low pressure is usually associated with humid air-perhaps precipitating.[1] A high pressure system is an air mass that contains denser air because its air is cooler and/or dryer than the surrounding air. Thus, its heavier air falls downward and away from the pressure system's center -like water being poured onto the ground. With high pressure systems, the weather will tend to become clear or clearing. A low pressure system is an air mass that has less dense air because its air is moister and/or warmer. Surrounding air draws inward toward the low system's center as the lighter air balloons upward, often causing clouds or precipitation because that moist air cools as it rises. You see this effect when air's invisible water vapor is forced to condense into droplets when it contacts the outside of a cold glass). But droplets won't form if the glass is only slightly cool ...thus, rising low pressure air will only produce rain if it gets up where the air is cool enough to condense the water vapor into droplets too heavy to be kept aloft by the rising air. (Clouds are simply water droplets that are small enough to be kept aloft). With very low pressure systems, storms are on the way (if they aren't there already) Clouds begin to form and move across the sky -thunderhead clouds forming when moist air is thrust very high. Sometimes tornadoes form when very high pressure air collides with very warm, moist low pressure air. "