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Name _____________ Due Date _________ Class_________ Welcome, Weather Experts! We at the Weather Central need your help. An air show and fireworks display are planned at Dayton, OH. These events will be held only if the weather is OK. The air show will be held at 2:p.m. The fireworks will start at 8:p.m. Event officials have asked us for timely, accurate weather forecasts. They will use your report to decide whether to hold these events. Several conditions determine the weather: Air pressure, fronts, temperature, dew point, winds, and clouds. As a meteorologist, you use maps, graphs, and charts to study these conditions. Then you make a prediction. You MUST use scientific terms and justify your predictions based on the weather maps and data collected. http://www3.cet.edu/weather/s1.html STORM-E Simulation Rubric Category 4 3 2 1 Preparation for initial prediction Completes maps and graphs and always uses them to support predictions and decisions. Completes maps and graphs and often uses them to support predictions and decisions. Completes maps and graphs but rarely uses them to support predictions and decisions. Completes maps and graphs but never uses them to support predictions and decisions. Weather prediction Correctly predicts weather using weather maps & data. Incorrect prediction. Uses weather maps & data. Guesses at a weather prediction. Makes no weather prediction. Content application Displays strong evidence that weather concepts were applied to make predictions and decisions. Displays some evidence that weather concepts were applied to make predictions and decisions. Displays very little evidence that weather concepts were applied to make predictions and decisions. Displays no evidence that weather concepts were applied to make predictions and decisions. Quality of work Provides work of the highest quality. (Typed or written legibly on clean, lined paper.) Provides work of a high quality. (Typed or written legibly on clean, lined paper.) Provides work of medium quality. (Neatly written in black or blue ink. Paper is disheveled.) Provides little work. (Illegible writing, pencil, torn or crumpled paper. Presentation Well developed thoughts. Complete sentences, no spelling or grammatical errors. Well developed thoughts. Contains less than 5 spelling or grammatical errors. Average thoughts. Contains less than 10 spelling or grammatical errors. Unorganized thoughts. More than 10 spelling or grammatical errors. Conditions for Severe Weather For thunderstorms to develop, the air must become unstable, and the following conditions must be present: • Abundant moisture, which means relatively high dew point readings. • Some "trigger" that will make the air lift, which could be an approaching cold front or upper air trough. • The right atmospheric conditions for unstable air, which means air pressure is dropping. Condition Weak possibility of severe weather Moderate possibility of severe weather Strong possibility of severe weather Air pressure pressure reading over threatened area 1010 to 1005 Humidity surface dew point readings Temperature cold front Wind Jet stream >1010 mb 1010 to 1005 mb < 1005 mb 55º F 56º to 64º F > 64º F Is a cold front moving into the area? If yes, how close is it? Is a trough approaching the area? If yes, how close is it? Fast Facts for the Air Pressure Team The readings are in millibars (mb). The average sea-level pressure is 1013.25 mb. Isobars are lines connecting places of equal air pressure. Air pressure changes help predict local weather. Rising air pressure usually means fair weather. Falling air pressure generally means stormy weather. On a weather map "H" shows the relative high pressure ("happy weather") and "L" shows the relative low pressure ("lousy weather"). These pressure readings are relative. That means there is no certain number that divides high from low. Low pressure surface winds, viewed from above in the Northern Hemisphere, blow counterclockwise and inward. High pressure surface winds, viewed from above in the Northern Hemisphere, blow clockwise and outward. Fast Facts for the Humidity Relative humidity is the amount of water vapor actually in the air divided by the amount of water vapor for the air to be saturated. This is assuming the temperature and pressure do not change. Relative humidity is stated as a percentage. The closer relative humidity gets to 100 percent, the more likely it is that clouds form. Dew point is the temperature to which air must be cooled to become saturated with water vapor. The closer air temperature gets to the dew point, the more likely it is that clouds form. Fronts are narrow zones between two air masses. The air masses have different temperatures, humidity, or both. Clouds and precipitation often form along a front. Fast Facts for the Temperature Generally, weather systems move across the United States from the west to the east. Fronts are narrow zones between two air masses. The air masses have different temperatures, humidity, or both. Clouds and precipitation often form along a front. Cold air is more dense than warm air. A cold front moves like a bulldozer. It pushes up a warm air mass in its path. The cold air advances, and the warm air retreats. Warm air is less dense than cold air. That means a warm front slides over top of a cold air mass. The warm air advances, and the cold air retreats. Warm air is less dense than cold air. That means cold air pushes warm air up. Next, the warm air rises until it eventually becomes cold. That makes it dense enough to move downward. Unstable air has warm air near the ground and cold air above. Unstable air can lead to billowing clouds and storms. Fast Facts for the Wind Jet Stream Jet streams are narrow corridors of very strong winds at altitudes from 30,000 to 50,000 ft. They blow in a wavy pattern from west to east across North America at speeds exceeding 60 knots. The jet stream steers surface lows (associated with troughs) and surface highs (associated with ridges) and the fronts anchored to them. Troughs of low pressure air bring generally cool, cloudy weather. Ridges of high pressure air bring generally warm, clear weather. When the jet stream is south of a given location, the weather tends to be relatively cold. When the jet stream is north of the same location, the weather tends to be relatively warm. Storms are more likely to develop on the leading (east) edge of a trough. Surface Winds The altitude of surface winds fluctuates depending on the terrain, air temperature, and air pressure. Surface winds can be located from ground level to approximately 3,000 feet. Changes in wind speed or direction may cause problems for small planes during takeoffs and landings. Authorities use the Beaufort Wind Scale to describe wind speed and strength.