Weather 2: Weather Mechanics Flashcards
What are gradient winds?
- Winds that flow perpendicular to the pressure gradient force and parallel to the isobars of the pressure system
- Found above 2,000’ AGL
What is the flow direction of gradient winds in a low pressure system?
Counter-clockwise
What is the flow direction of gradient winds in a high pressure system?
Clockwise
What forces causes the flow direction of gradient winds?
- Pressure gradient force
- Coriolis force
What are surface winds?
- Winds that flow at a 45° angle across isobars
- Found below 2,000’ AGL
What is the flow direction of surface winds in a low pressure system?
Counter-clockwise around and into the low system
What is the flow direction of surface winds in a high pressure system?
Clockwise around and out of the high system
What forces causes the flow direction of surface winds?
- Pressure gradient force
- Coriolis force
- Surfrace friction
Jet Stream
A narrow band of strong winds of 50kts or more that stays vertically and horizontally around the hemisphere in wave-like patterns (flows west to east)
What are some characteristics of the jet stream? (Average wind speed, average height, segments, thickness)
- Average wind speed: 100-150kts but can reach up to 250kts
- Average height: 30,000’ MSL
- 1000-3000 miles (length)
- 100-400 miles (width)
- 3000-7000 ft (thickness)
Sea breeze
- An onshore wind blowing from sea to land
- Can reach 15-20kts
- Usually occurs during the day
Caused by the warmer air over the land rising (because it is less dense) and the colder air from the ocean moving in and going under the rising warmer air
Land Breeze
- An offshore wind blowing from land to sea
- Usually not as strong as the sea breeze
- Usually occurs during the night
Caused by the warmer air over the ocean rising (because it is less dense) and the colder air from the land moving in
What are the cloud types and their respective altitudes?
- Low Clouds (surface - 6,500’ AGL)
- Middle Clouds (6,500’ AGL - 20,000’ AGL)
- High Clouds (above 20,000’ AGL)
- Special clouds with extensive vertical development
What determines cloud height?
The height of the base of the cloud
What are the cloud forms?
- Cumuliform
- Stratiform
Describe cumuliform clouds.
- Comes from moist, unstable air
- Associated with showery precipitation
- Large puffy clouds with more definite shapes
Describe stratiform clouds.
- Comes from moist, stable air
- Associated with steady precipitation
- Widespread with no definable shape
Describe Special Clouds with Extensive Vertical Development.
Clouds that usually has a base at low/middle cloud height and has tops that extend through high cloud heights
Three main types:
1. Nimbostratus
2. Towering cumulus
3. Cumulonimbus
Describe Low Clouds.
- From surface to 6,500’ AGL
- Mainly made of water droplets
- If you see “nimbo” or nimbus” that means violent/heavy precipitation from these clouds
Describe Middle Clouds.
- From 6,500’ AGL to 20,000’ AGL
- Made of ice crystals, water droplets, or both
- Has the prefix “alto”