Weather around Fronts and Cyclogenesis
- 1. WEATHER AROUND FRONTS AND CYCLOGENESIS
- 2. Weather Before • Weather is influenced by the air mass over a region • When a front begins to move over a region the weather changes • Once a front has moved pass a region the weather will shift to the new air mass in place • When a front approaches the pressure drops
- 3. Approaching Front • Cold Front • Rapid cloud development, cumulus and cumulonimbus. • Heavy precipitation, over a short time • In the Spring and Summer cold fronts will have thunderstorms, some may be severe • Front may pass through as fast as a few hours • Warm Front • Layered cloud development, cirrus clouds are indicators of an approaching warm front • Steady precipitation, over an extended time • Front may take several days to pass through
- 4. Approaching Front • Occluded Front • Associated with large areas of rainy and severe weather • This is part of a low pressure system • Stationary Front • Rainy weather around the front • Passage may take several days because the front is not moving, the front “stalls”
- 5. Behind the Front • After a front passes the weather will change. • After a cold front the: • Temperatures are cooler • Air is drier • Pressure is higher • After a warm front the: • Temperatures are warmer • The air is moist • Pressure is higher
- 6. Wrap Up • How does the weather change during and after a cold front? • What type of weather is associated with occluded and stationary fronts?
- 7. Cyclogenesis • Cyclogenesis is the development of a low pressure system • Low pressure systems in the middle latitudes are called mid-latitude cyclones • Mid-latitude cyclones usually develop along either the polar jet stream or the sub tropical jet stream • A mid-latitude cyclone goes through a life cycle of four stages
- 8. Before the cyclone • A stationary front forms a boundary between a cold and warm air mass • These fronts can be found along the jet stream
- 9. Stages of a cyclone • Early Stage: A wave or “kink” in the front develops. • The wave begins to rotate and the low pressure system is born • Precipitation begins to develop
- 10. Stages of a cyclone • Open Stage: The drier, cooler, more dense air begins to close in on the warm air. • This stage the warm and cold fronts become easily noticeable and more developed.
- 11. Stages of a cyclone • Occluded Stage: The low pressure system becomes fully developed. • The cold front catches-up to the warm front and creates an occluded front, this is part of the low pressure system. • The storm is biggest in this stage
- 12. Stages of a cyclone • Dissolving Stage: The occluded front becomes larger and the supply of warm air is cut-off and pushed aloft • The low-pressure begins to gradually dissipate
- 13. Wrap-up • Draw in an L where the low pressure is located. • Draw in where the fronts are located. • Which directions do all mid-latitude cyclones move? Why? • What stage is the cyclone in?