Synoptic Features Flashcards
What are the two basic cloud forms?
- Stratiform or stratus-type clouds
- Cumuliform or cumulus-type clouds
What are the four types of cumuliform clouds?
- Cumulus (CU)
- Towering cumulus (TCU)
- Cumulonimbus (CB)
- Altocumulus castellanus (ACC)
What are CU clouds?
Cumulus clouds that develop vertically in form of rising mounds, domes, or towers
What are TCU clouds?
Towering cumulus clouds is when the height of TCU exceeds the width with distinctive cauliflower top means showers below
What are CB clouds?
Cumulonimbus clouds are thunderclouds that contain thunderstorm activity; appear heavy and dense with considerable vertical extent in form of mountain or tower
What are ACC clouds?
Altocumulus castellanus clouds that are white, grey, or both; often a telltale sign of impending thunderstorm development
What is a high-pressure area?
Region where atmospheric pressure greater than its surrounding environment with pressure values increasing towards centre; air circulates clockwise
What is a low-pressure area?
Region where atmospheric pressure is lower than its surround environment, with pressure values decreasing towards centre; air circulates counter-clockwise
What is Coriolis force?
Caused by Earth’s rotation which affects the direction of air movement
How does the Coriolis force occur in southern hemisphere?
Coriolis force deflects moving air to left because rotating Earth has clockwise spin
What is Buys Ballot’s Law?
Wind at your back in the northern hemisphere, area of lower pressure lies to your left
What is veering?
When wind makes clockwise change in direction
What is backing?
When wind makes a counter-clockwise change in direction
What are the five lifting agents?
- Convection
- Orographic lift
- Frontal lift
- Mechanical turbulence
- Convergence
What is convection?
Air is heated below by contact with Earth’s surface
What is orographic lift?
Air is forced up sloping terrain by wind
What is frontal lift?
Air is forced to rise by a wedge of colder and denser air
What is mechanical turbulence?
Friction between air and ground causes air to be stirred up into series of areas of swirling motion known as eddies
What is convergence?
Occurs at centre of low-pressure systems; air converges at this point and is forced to rise, resulting in cloud and precipitation
What causes CB clouds to form?
- Lifting action
- Unstable air mass
- High moisture content
What is air mass?
Large section of troposphere with relatively uniform properties of temperature and moisture in the horizontal
What is a front?
Transition zone between two air masses
What are the different types of fronts?
- Cold front
- Warm front
- Stationary front
What is a cold front?
Transition between advancing cold air and warm air; identified by arrowhead
