WEATHER, WEATHER ALL AROUND Part 2
Jet Stream • The term “jet stream” is often used to refer to the rivers of wind high in the atmopshere – above about 20,000 feet – that steer storms. • These winds not only steer storms, but also help determine the locations of areas of high and low air pressure at the Earth’s surface.
Weather Fronts • Fronts are the boundaries between areas of high atmospheric pressure and low atmospheric pressure that typically bring unsettled weather.
COLD FRONT • A COLD FRONT has cold air behind it that pushes abruptly underneath the warm air it encounters. As the warm air is forced upward, water vapor condenses into clouds and rain, which can sometimes be heavy along the front. • A cold front is often characterized by quick changes and steady precipitation, followed by showery precipitation.
WARM FRONT • A WARM FRONT has warm, moist air behind it that rises over the colder air it encounters. Rain may fall behind the front as the warm, rising air condenses. • A warm front generally has a long frontal boundary -- the area where changes occur.
STATIONARY FRONTS • STATIONARY FRONTS occur where warm and cold air meet but neither wins out. • Unsettled weather can occur over a wide area near the frontal boundary. • A noticeable temperature change and/or shift in wind direction is commonly observed when crossing from one side of a stationary front to the other.