Weather Notes Completed PDF

# Air Masses, Fronts and Predicting Weather Notes ## Key Term - Air Mass ## Supporting Information - A large body of air with similar: - Temperature - Humidity - Air Pressure - They can travel great distances and influence our local weather. ## Types of Air Masses - 4 Major Masses t...

# Air Masses, Fronts and Predicting Weather Notes ## Key Term - Air Mass ## Supporting Information - A large body of air with similar: - Temperature - Humidity - Air Pressure - They can travel great distances and influence our local weather. ## Types of Air Masses - 4 Major Masses that influence North America's Weather: - Maritime Tropical - Continental Tropical - Maritime Polar - Continental Polar ### Maritime Tropical - Warm, humid air mass. - Over tropical oceans. - In summer, they bring showers & thunderstorms. - In winter, they bring heavy rain or snow. ### Maritime Polar - Cool, humid air mass. - Over Pacific and Atlantic oceans. - Brings fog, rain, and cooler temperatures year round. ### Continental Tropical - Hot, dry air mass. - Forms over the Southwest. - Covers the smallest area compared to other air masses. ## How do air masses move? - When you see maritime, think ocean, so -> humid air - When you see continental, think land, so -> dry air - When you see polar, think north pole, so -> cold air - When you see tropical, think island, so -> warm/hot air - When air masses move into an area and interact with other air masses, we see weather change. - In the U.S., the prevailing westerlies and the jet stream move air masses towards us in P.A. - Both move west to east. ## Types of Fronts? - Fronts are the boundary where air masses meet. - When two air masses meet, they don't mix well due to their differing temperature and humidities. - Storms and changing weather are typically fronts. - Four types of Fronts: - Cold Fronts - Warm Fronts - Stationary Fronts - Occluded Fronts - The direction the triangles or semicircles face show you where the front is moving. ## Types of Fronts ### Cold Fronts - Denser cold air slides under lighter warm air: - Move in fast. - Warm air is pushed up quickly, condenses, forms thunderstorms. - Can cause abrupt weather changes. - Once it has moved into an area, cooler, dry air, with clear skies. ### Warm Fronts - Warm, less dense air pushes in over cold air: - Rain or snow occurs if air is humid. - Scattered clouds form if air is dry. - Move slowly, bring rainy/cloudy weather for days. - After passing, weather is warm and humid. ### Stationary Fronts - When a warm and cold front meet but cannot move each other, they: - Water vapor in the warm air condense into clouds and precipitation. - Can bring many days of clouds and rain. ## Types of Fronts ### Occluded Fronts - Warm air is trapped between 2 cold air masses - Dense, cool air moved underneath both sides - Warm air gets pushed up and is cut off from the ground. - As warm air rises, it condenses into precipitation. ## Weather Forecasting ### Meteorologist - A scientist who uses information from the National Weather Service to try and predict weather & prepare weather forecasts. ## Meteorologist Collect Data - Direct Observations: - Looking at the sky and clouds. - Use Instruments: - Weather Balloons - Weather balloons, satellites, barometers, weather stations, etc. - Computers to analyze weather data. ## Weather Satellites - Designed to take pictures of clouds and storms from space to send back to data centers. ## Weather Stations - Collects data on temperature, humidity, solar radiation, and wind direction. - Weather gathered from the ground can measure temperature, air pressure, relative humidity, and wind speed/direction. ## Computer Forecasts - Computers are often used in conjunction with weather balloons, satellites, and weather stations. - Computers process the information gathered and use them to help forecasters make predictions. - When new data arrives, computers revise the forecast in seconds. ## Reading Weather Maps - Computers can help create diagrams known as weather maps. - A weather map is a "snapshot" of the conditions at a specific time over a large area. ### Weather Service Maps - Show data from many local weather stations all over the country. - Summarize data using map symbols. - There are different kinds of weather maps including weather service maps and newspaper weather maps. ### Weather Service Maps - Advanced weather maps with curved lines. These lines connect places where conditions are similar. - Include: - IsoBARS - Lines on weather maps that connects places on the map with the same air pressure. - IsoTHERMs - Lines on weather maps that connect places on the map with the same temperature. ## Severe Storms ### Storm - A violent disturbance in the atmosphere - Sudden change in air pressure causes rapid air movement. - There are several types: - Thunderstorm - Hurricanes - Tornado - Snowstorms ### Thunderstorms - Small storm with heavy precipitation, thunder, and lightning. - Form in cumulonimbus clouds. - Typically occurs along a cold front - Many have: - Lightning - A spark or electrical discharge that can jump within a cloud, cloud to cloud, or cloud to ground. ## Hurricanes - Thunder - When rapidly heated air expands from lightning - You see the lightning before thunder since light travels faster than sound. - A tropical storm that has winds of 73 MPH-198 MPH. - Can grow up to 600 miles wide. - Form in the Atlantic, Pacific and Indian Oceans. - Most common in August-October. - Begin over warm water as low pressure areas. - Winds spiral inwards toward area of low pressure. - Inside the storm are bands of clouds, high winds, & heavy rains. - Last longer than other storms - several days. - Once they hit land they lose their energy source (warm water). ## Hurricane Damage and Safety ### Damage - High winds - Severe flooding - Storm surge - Dome of water that sweeps across the coast where the hurricane lands - Erodes Beaches - Use Saffir-Simpson Hurricane Scale - Category 1-5 based on wind speed ### Safety - Hurricane "watch" - conditions are possible within the area. ## Tornados - Hurricane "warning" - conditions are expected in the next 36 hours. - Evacuate - Avoid flooding by getting to high ground. ### Tornado Damage and Safety ### Damage - A fast spinning column of air that reaches down to Earth's surface from a cumulonimbus cloud. - Thunderstorms can lead to tornadoes. - Low pressure in the center and strong winds spinning around. - Forms in a funnel shape. - Short-lived (over a few minutes). - High winds up to 300 MPH. - Only a few meters across. - Common where cold, dry air meets moist air. - Air masses meet in the Great Plains - Nicknamed "Tornado Alley". - Most common during spring and early summer. - Low pressure inside sucks dust & debris into the funnel. - High winds and flying objects can damage homes, tear up roads and trees etc. - Ranked using the Enhanced Fujita Scale: - Some damage (FO) - Massive damage (F5) ### Safety - Tornado "warning" - tornado has been seen in the area - MOVE ASAP - Storm shelter - Basement - Middle of the ground floor of a building or home - Stay away from windows and doors - Move under a sturdy piece of furniture - If outside, lie flat in a ditch. ## Snowstorms - Year round, most water begins in clouds as snow. - If the air is below 0 °C or 32°F all the way to the ground, it will stay snow if not turns to rain.