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Types of Fronts Stationary Front a Front That Is Not Moving Types of Fronts Stationary front A front that is not moving. Types of Fronts Cold front is a leading edge of colder air that is replacing warmer air. Types of Fronts Warm front is a leading edge of warmer air that is replacing cooler air. Types of Fronts Occluded front: When a cold front catches up to a warm front. Types of Fronts Dry Line Separates a moist air mass from a dry air mass. A.Cold Front is a transition zone from warm air to cold air. A cold front is defined as the transition zone where a cold air mass is replacing a warmer air mass. Cold fronts generally move from northwest to southeast. The air behind a cold front is noticeably colder and drier than the air ahead of it. When a cold front passes through, temperatures can drop more than 15 degrees within the first hour. The station east of the front reported a temperature of 55 degrees Fahrenheit while a short distance behind the front, the temperature decreased to 38 degrees. An abrupt temperature change over a short distance is a good indicator that a front is located somewhere in between. B. Warm Front. • A transition zone from cold air to warm air. • A warm front is defined as the transition zone where a warm air mass is replacing a cold air mass. Warm fronts generally move from southwest to northeast . The air behind a warm front is warmer and more moist than the air ahead of it. When a warm front passes through, the air becomes noticeably warmer and more humid than it was before. Diagram of Warm and Cold Fronts Looking at a Cold Front in more detail Another view of a Cold Front Looking at details of a Warm Front Another view of the Warm Front C. Stationary Front a front that is not moving. When a warm or cold front stops moving, it becomes a stationary front. Once this boundary resumes its forward motion, it once again becomes a warm front or cold front. A stationary front is represented by alternating blue and red lines with blue triangles pointing towards the warmer air and red semicircles pointing towards the colder air. D. Occluded Front - when a cold front overtakes a warm front. A developing cyclone typically has a preceding warm front (the leading edge of a warm moist air mass) and a faster moving cold front (the leading edge of a colder drier air mass wrapping around the storm). North of the warm front is a mass of cooler air that was in place before the storm even entered the region. As the storm intensifies, the cold front rotates around the storm and catches the warm front. This forms an occluded front, which is the boundary that separates the new cold air mass (to the west) from the older cool air mass already in place north of the warm front. Symbolically, an occluded front is represented by a solid line with alternating triangles and circles pointing the direction the front is moving. Formation of an Occluded Front Special situation of an Occluded Front Isobars: connect areas with equal air pressure The distance between the isobars is called the pressure gradient • The closer the isobar lines, the greater the change in air pressure, and the greater/faster the winds speeds. On the previous weather map ; Dew points east (ahead) of the dry line shown above range from the upper 50's to low 70's with winds from the southeast. West of the dry line, dew points were in the 20's and 30's, a decrease of nearly 50 degrees. Air temperatures ahead of the dry line were generally in the 70's and 80's while behind the dry line, temperatures ranged from the mid 80's to mid 90's. Drier air behind dry lines lifts the moist air ahead of it, triggering the development of thunderstorms along and ahead of the dry line (similar to cold fronts). It is not uncommon for tornadic super cells to develop along a dry line. .
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