Describe the characteristics, including where it forms, of the following air masses: Continental polar Continental tropical Maritime polar Maritime tropical Starter

Objectives P. 56 Describe the formation of a front Differentiate among formation of a warm front, cold front, stationary front, and occluded front. Describe weather patterns associated with each type of front

20.2 Fronts  When two air masses meet, they form a front, which is a boundary that separates two air masses.

20.2 Fronts  Warm Fronts A warm front forms when warm air moves into an area formerly covered by cooler air.

Formation of a Warm Front A warm front forms when warm air glides up over a cold, dense air mass. The affected area has warmer temperatures and light to moderate precipitation.

 Cold Fronts A cold front forms when cold, dense air moves into a region occupied by warmer air.

Formation of a Cold Front A cold front forms when cold air moves into an area occupied by warmer air. The affected area experiences thunderstorms if the warm air is unstable.

20.2 Fronts  Stationary Fronts Occasionally, the flow of air on either side of a front is neither toward the cold air mass nor toward the warm air mass, but almost parallel to the line of the front. In such cases, the surface position of the front does not move, and a stationary front forms.

Stationary Front Air flow on either side of the front is neither toward the cold air mass or toward the warm air mass. Have blue triangles on one side and red semicircles on the other of a weather map. Have gentle to moderate precipitation.

 Occluded Fronts When an active cold front overtakes a warm front, an occluded front forms.

Formation of an Occluded Front An occluded front forms when a cold front overtakes a warm front, producing a complex weather pattern.

20.2 Fronts  Middle-latitude cyclones are large centers of low pressure that generally travel from west to east and cause stormy weather. Middle-Latitude Cyclones

Satellite View of a Mature Cyclone

Middle-Latitude Cyclone Model

20.2 Fronts  More often than not, air high up in the atmosphere fuels a middle-latitude cyclone. Air Flow Aloft

Movements of Air High in the Atmosphere Movements of air high in the atmosphere fuel the cyclones and anticyclones near Earth’s surface.

Fronts Foldable (page 55) Create a four-door foldable with the four main fronts that affect our weather. Include: Name of the Front (outside) Description of each type;How it forms; Weather Associated with; (inside) Drawing of Front Type with Symbols (inside) Use correct color

Post Test (p. 114) 1.What is a middle latitude cyclone? 2.What is the role of air flow aloft? 3.Compare and contrast warm fronts and cold fronts