Atmospheric Movement and Local Weather

*Fronts

*When convection and winds cause air masses to move, they bump into one another.

*The area where two air masses meet is called a front.

*Most severe weather occurs near frontal boundaries.

*Cold Front- Cold air meets warm air- Fast moving and stormy, severe weather is likely

*Cold Front Symbol

*Moves in the Direction of the

Triangles

*Cold, dense air is moving toward warm, less dense air.

*The warm air is pushed up to cool and form clouds as the cooler air replaces it.

*The air on the front side of the boundary line is warmer than the air on the back side of the boundary line.

*These fronts are usually fast moving and bring stormy weather and heavy precipitation followed by clearing skies and higher pressure.

*Warm Front- Warm air meets cold air- Slow moving with less severe weather

*Warm Front Symbol

*Moves in the Direction of the

Semi-Circles

*Warm air is moving toward cold air.

*The warm, less dense air slides over the cold, more dense air.

*The air on the front side of the boundary line is cooler than the air on the back side of the boundary line.

*These fronts usually move slowly and bring steady rain or snow over many days.

*Stationary Front

*Warm and cool air masses that are not strong enough to move one another

*Sits still for a long period of time

*Stationary Front Symbol

*Stay in One Area

*These fronts occur when neither the cool nor warm air masses are strong enough to replace each other.

*They tend to stay in an area for a long period of time, often bringing long periods of precipitation and clouds.

*Occluded Fronts

*Two cooler air masses meet and force a warm air mass aloft.

*Brings cool temperatures and large amounts of rain or snow.

*Followed by clear skies and drier air.

*Occluded Front Symbol

*Occluded Fronts

*This is when a warm air mass is caught between two cold air masses.

*The colder air mass moves under the warm air mass and pushes it up.

*The colder air mass then moves forward until it meets a cold air mass that is warmer and less dense.

*The colder air mass moves under this air mass and pushes it up.

*Brings clear skies and drier air.

*Land Breeze

*Sea Breeze

*Sea Breeze and Land Breeze

Simulation

http://www.classzone.com/books/earth_science/terc/content/visualizations/es1903/es1903page01.cfm?chapter_no=visualization

*Land and Sea Breezes

*The heating and cooling of water and land produces land breezes and sea breezes.

*High pressure moves toward low pressure, pushing the warm air upward.

*As warm air rises, cooler air moves in and replaces it.

*The Earth’s Insulator

*The Sun heats the water and land every day.

*Land heats up rapidly, but cools off rapidly.

*Desert

*Water heats up slowly, but cools off slowly.

*Swimming at night

*The heat retained by the oceans is what keeps our planet insulated.

*Weather Maps

*Weather Maps

*Weather is the atmospheric condition at a certain time and place.

*Weather maps are used to show current weather conditions in an effort to predict future weather conditions.

*You need to know what each symbol means and how to interpret them to forecast the weather.

*Air Pressure and Wind

*Air pressure is measured with a barometer in millibars.

*Millibars are represented by connected lines of equal pressure. This is a lot like the topographic map lines.

*The closer together the lines are, the faster the wind speed.

*The farther apart the lines are, the slower the wind speed.

*High Pressure

*Moves toward Low Pressure

*Cooler, dense air close to the surface of the Earth.

*Surrounded by winds flowing in a clockwise direction.

*Usually brings dry conditions and fair skies.

*Low Pressure

*High pressure will move toward low

pressure.

*Warmer, less dense air above the Earth’s surface

*Surrounded by winds moving in a counterclockwise direction.

*Associated with the formation of storms.

*High and Low Pressure Circulation

*Pressure Force

*Front symbols you may see on a

weather map