Synoptic Charts Flashcards
What is an airstream?
A flow of air from one region to another
What conditions are generally associated with warm air streams?
Cooling of the surface layers generally creates an inversion and stable conditions as up layers remain warm
What conditions are generally associated with cold air streams?
Surface layers generally warm due to latitudinal heating while upper layers stay cool resulting in steep ELR’s creating unstable conditions
Where and what is the Inter-Tropical Convergence Zone?
Found near the equator, it is a boundary between 2 airstreams origination in the northern and Southern Hemispheres
What weather is generally associated with a high (anti cyclone)?
- Subsidence and subsidence inversions
- Limits vertical development of cloud
- Stable conditions
- Poor visibility below inversion
What weather is generally associated with a low (depression)?
- Rising air / convection
- Unstable conditions with rain and cloud
- Generally good visibility
What weather is generally associated with a col (neutral area between 2 highs and 2 lows)?
- Light and variable winds
2. Poor visibility
What do STREAMLINES indicate on a synoptic chart? (In place of isobars)
Average wind direction
What is the minimum wind speed for classification of a cyclone?
34kts AROUND THE EYE
Where do cyclones typically form?
5 to 15 degrees from the equator
What are the 4 stages of a cyclone?
- FORMATIVE
- IMMATURE
- MATURE
- DECAYING
Describe the FORMATIVE stage of a cyclone?
- Existing depression deepens
- Pressure decreases
- Wind speed increases (greater than 34kts)
Describe the IMMATURE stage of a cyclone?
- Pressure falls below 1000HPA
2. Wind speeds increase with continued development to in excess of 63kts
Describe the MATURE stage of a cyclone?
- Pressure steady
- Storm reaches its largest size
- Eye may fluctuate in diameter due to internal forces
Describe the DECAYING stage of a cyclone?
- Pressure begins to rise
- Storm area contracts
- Energy supply interrupted by land or cooler water
