Matt Aufman NSF North Mississippi GK-8 November 2005 Weather! Matt Aufman NSF North Mississippi GK-8 November 2005 NSF North Mississippi GK-8

NSF North Mississippi GK-8 Temperature You will usually see temperature measured in °F for maps of the United States Maps of foreign countries will usually be measured in °C NSF North Mississippi GK-8

NSF North Mississippi GK-8 Relative Humidity The relative humidity tells us how “full” the air is at the time of measurement. For example, 90% relative humidity means that at that moment the air is holding 90% of the maximum amount of water it could. NSF North Mississippi GK-8

NSF North Mississippi GK-8 Cloud Cover Symbols You will often see the circles drawn on a weather map NSF North Mississippi GK-8

NSF North Mississippi GK-8 High and Low Pressure Areas High pressure causes air to sink Usually results in several days of clear sunny skies Air rises in low pressure areas and forms water droplets Usually results in rain and storms NSF North Mississippi GK-8

NSF North Mississippi GK-8 Air Masses There are two types of air masses: 1. Continental Polar air masses 2. Maritime Tropical air masses NSF North Mississippi GK-8

NSF North Mississippi GK-8 Fronts A front is the boundary separating air masses of different densities Fronts extend both vertically and horizontally in the atmosphere NSF North Mississippi GK-8

NSF North Mississippi GK-8 Fronts: Five Types of Fronts 1. Cold Front: The zone where cold air is replacing warmer air In U.S., cold fronts usually move from northwest to southeast Air gets drier after a cold front moves through NSF North Mississippi GK-8

NSF North Mississippi GK-8 Fronts: Five Types of Fronts 2. Warm Front: The zone where warm air is replacing colder air In U.S., warm fronts usually move from southwest to northeast Air gets more humid after a warm front moves through NSF North Mississippi GK-8

NSF North Mississippi GK-8 Fronts: Five Types of Fronts 3. Stationary Front: When either a cold or warm front stops moving When the front starts moving again it returns to either being a cold or warm front NSF North Mississippi GK-8

NSF North Mississippi GK-8 Fronts: Five Types of Fronts 4. Occluded Front: Formed when a cold front overtakes a warm front This occurrence usually results in storms over an area In U.S., the colder air usually lies to the west NSF North Mississippi GK-8

NSF North Mississippi GK-8 Fronts: Five Types of Fronts 5. Dry Line (Dew Point Front): Boundary separating a dry air mass from a moist air mass This occurrence can result in tornadoes being formed Usually found in western part of U.S. NSF North Mississippi GK-8

NSF North Mississippi GK-8 Clouds: Five Types of Clouds 1. High-Level Clouds: Usually found at greater than 20,000 ft. Usually made of ice crystals Examples include Cirrus, Cirrostratus NSF North Mississippi GK-8

NSF North Mississippi GK-8 Clouds: Five Types of Clouds 2. Mid-Level Clouds: Usually found between 6,500 and 20,000 ft. Usually made of water droplets, but can be made of ice Example is altocumulus NSF North Mississippi GK-8

NSF North Mississippi GK-8 Clouds: Five Types of Clouds 3. Low-Level Clouds: Usually found lower than 6,500 ft. Low, lumpy clouds that produce weak to moderate precipitation Examples include Nimbostratus and Stratocumulus NSF North Mississippi GK-8

NSF North Mississippi GK-8 Clouds: Five Types of Clouds 4. Vertically developed: These clouds are thick and puffy and extend very far upwards Examples include Cumulonimbus and Fair Weather Cumulus Ordinary Cumulus clouds can quickly become Cumulonimbus clouds that start strong thunderstorms NSF North Mississippi GK-8

NSF North Mississippi GK-8 Clouds: Five Types of Clouds 5. Other: These are miscellaneous clouds These clouds do not really fit into any category, and all have different characteristics Examples include billow clouds, contrails, mammatus, orographic, and pileus NSF North Mississippi GK-8

NSF North Mississippi GK-8 Weather Maps: Pressure & Temperature NSF North Mississippi GK-8

NSF North Mississippi GK-8 Weather Maps: Doppler Radar Maps NSF North Mississippi GK-8

NSF North Mississippi GK-8 Summary Temperature: Usually in °F, need to convert to °C High pressure areas cause sunny weather; low pressure areas cause rain and storms Two Types of air masses: 1. Continental Polar 2. Maritime Tropical NSF North Mississippi GK-8

NSF North Mississippi GK-8 Summary (continued) Five types of fronts: 1. Cold 2. Warm 3. Stationary 4. Occluded 5. Dew Point (Dry Line) Five types of clouds: 1. High Level 2. Mid Level 3. Low Level 4. Vertically developed 5. Miscellaneous NSF North Mississippi GK-8

NSF North Mississippi GK-8 Sources Palmer, Chad and Evans, David. May 20, 2005. Occluded fronts can signal weakening of storm. Accessed 28 October 2005. http://www.usatoday.com/weather/tg/wofront/wofront.htm Palmer, Chad and Kepple, Kevin. May 20, 2005. High-pressure systems brings sunny days. Accessed 27 October 2005. http://www.usatoday.com/weather/tg/whighp/whighp.htm Palmer, Chad and Kepple, Kevin. May 20, 2005. How low pressure systems affect weather. Accessed 27 October 2005. http://www.usatoday.com/weather/tg/wlowpres/wlowpres.htm Weather World 2010, University of Illinois. No date of publication given. Reading and Interpreting Weather Maps. Accessed 21 October 2005. http://ww2010.atmos.uiuc.edu/(Gh)/guides/maps/home.rxml NSF North Mississippi GK-8