Wednesday , November 16th

1. Wednesday, November 16th • Attendance • Go over Unit Test 3 • Make-up work and/or weather dvd

2. Unit 11 Weather Forecasting

3. I. Weather Maps • A. Synoptic forecasting is based on looking at a summary of the total weather picture at a particular time. • A synoptic weather map is made by measuring atmospheric weather variables at thousands of weather stations around the world.

5. I. Weather Maps • B. Field – a region of space that has a measurable quantity at every point. • Elevation is measured by contour lines on a topographic map. • Temperature is measured by isotherms on a weather map. • Atmospheric pressure is measured by isobars on a weather map. • Isolines are “generic” lines that connect equal values.

6. I. Weather Maps • C. Air masses are large regions of air with fairly uniform characteristics like temperature, humidity, winds and air pressure. • Identified by the temperature and moisture content. • The code has two letters. • The first letter is lower case and represents moisture. • m = maritime = moist • c = continental = dry • The second letter is upper case and represents temperature. • T = tropical = warm • P = Polar = cool • A = Arctic = frigid (very cold)

8. I. Weather Maps • C. Air Masses • The boundaries between air masses are called frontal boundaries. FRONTS • What causes air masses to move across the Earth?

9. I. Weather Maps • Answer: Planetary winds

10. I. Weather Maps • D. Weather Fronts • There are usually several different air masses moving across the United States. • When different air masses meet, very little ______ occurs. • There is a frontal boundary and there is a rapid change in the weather. It is usually unsettled and rainy.

11. 1. Weather Maps • D. Weather Fronts • There are 4 main types of frontal boundaries • 1. Cold Fronts occur when cold air moves in on warmer air. • The cold air is more dense and stays near the ground as it pushes up the warmer air in its way. • The warm air that is pushed up cools. It can no longer hold as much water vapor and heavy precipitation occurs.

14. Weather Maps • D. Fronts 2. Warm Fronts occur when a warm air mass runs into a cold air mass. The warmer air is forced up and it cools. It can no longer hold as much water vapor. Heavy precipitation occurs.

17. Weather Maps D. Fronts 3. Stationary Fronts occur along the boundary between a warm air mass and a cold air mass when neither move. The warm air will eventually move on top of the cold air and there will be precipitation for a few days until a new front moves in.

20. I. Weather Maps • D. Fronts • 4. Occluded Fronts occur when a cold air mass runs into another cold air mass (a warm air mass might be stuck between them). • Since cold air masses are more dense, they travel faster. • Large scale precipitation occurs.

23. I. Weather Maps • E. Cyclones are low pressure systems.

24. Weather maps • F. Anticyclones are high pressure systems.

25. I. Weather maps • G. Jet Streams are bands of easterly moving air made by convection cells within the atmosphere. The winds can blow up to 200 mph. Jet streams help steer weather patterns across our continent.

27. II. Weather Forecasting • Synoptic weather forecasting uses charts, maps and computers. • Statistical weather forecasting looks at past weather frequency. • Weather patterns become evident when weather variables are observed, measured and recorded.

28. II. Weather Forecasting _________ is Radio Detection And Ranging bounces electromagnetic energy off of clouds to get images on a computer Doppler Radar is a special type of radar that gives accurate readings and is able to determine the conditions necessary for tornadoes

30. Doppler Radar

31. II. Weather Forecasting • _____________ images show the position of clouds and storms as they travel over the earth.

32. III. Energy in the Atm. • Earth’s systems have internal and external heat engines • Internal: friction, radioactivity, residual heat from formation • External: sun’s heat, trapped Earth’s heat

33. III. Energy in the Atm. • Precipitation results from the heating of the atmposphere from the sun. • The transfer of energy from the atmosphere, hudrosphere and th eEarth’s interior results in the formation of regions with different densities. • Density differences between regions results in the motion of air and weather.

34. IV. Hazardous Weather • The loss of property, personal injury and loss of life can be reduced by effective emergency preparedness.

35. IV. Hazardous Weather • Thunderstorms • Updrafts and down drafts of air occur because of unequal heating • Particles of air build up electrical charges as the air goes up and down • Lightening occurs because of the electrical charges • **Stay away from trees, don’t use electrical appliances, don’t use plumbing

37. IV. Hazardous Weather • ____________ are small, brief disturbances that usually develop over land from intense thunderstorms • Hot moist air meeting with cold, dry air • Narrow: 100 feet in diameter • Can last up to an hour • Wind speeds up to 320 mph • Occur in spring and summer • ****Go into the basement and cover your head, stay away from windows.

40. IV. Hazardous Weather • ________________ are regions of very low pressure, cyclones, that form over open water, huge swirling wind mass • Lose energy as travels over land • Winds of 74 mph or more, storm surges, causes massive flooding • June to November • ***Evacuate