UNIT 7

1. UNIT 7 METEOROLOGY

2. A. WEATHER AND WEATHER VARIABLES a short term condition of the atmosphere Weather is: _____________________________________________ It is a result of the interrelationship of temperature, humidity, air pressure and winds. Temperature is: ___________________________________________ _________________________________________________________ a measure of the average amount of heat energy in the atmosphere different It is affected by the amount of sunlight. Other factors such as ________, ________, i.e._______________________, _________, _____________ and ______________________________ contribute to a variety of temperature conditions. surfaces land or water; dark or light altitude cloud cover movement of air masses Scientists use three different temperature scales and may need to convert from one to another (Page 13 of the ESRT.)

3. Heat is not the same thing as temperature. Heat is a form of kinetic (motion) energy. Atoms or molecules of a substance are always moving. The more heat energy they have, the __________ they move. faster Temperature is a measure of the __________ kinetic energy one atom or molecule has (how fast it’s moving). Heat is the _______ kinetic energy found in a material. average total Example: A teaspoon of boiling water has a higher temperature (is hotter) than a bathtub full of lukewarm water. However, the bathtub water has more heat energy because _____________________________ ________________________________________________________. the total volume of moving water molecules is much greater ( a lot of mild temperature vs a little hot) Scientifically, heat is energy being transferred from one material or object to another. Heat always flows from a ______ material or object to a _________ one. hot cold

4. Heat In Air (70oF) Heat Out Ice Tea (40oF) Coffee (110oF) Example: Heat flows from a hot cup of coffee into a cooler room, so the coffee loses heat (cools). Heat flows from a warmer room into a glass of cooler iced tea. Therefore, the iced tea warms up. Heat is transferred in one of three ways. Radiation: _________________________________________________ carried as electromagnetic waves through space (like light) Conduction: _______________________________________________ carried along a material or through touch (mostly solids) Convection:_________________________________________________ __________________________________________________________ carried by moving liquid or gaseous substances; this is how most heat is transported in the oceans and atmosphere

5. Radiation Space is so empty that there is not much matter to warm up. Heat waves travel as infrared electromagnetic radiation. When the infrared waves strike matter, they cause the matter to warm up. Conduction When heat is conducted, it is led from the heat source by traveling along a physical object. The person on the left was holding a metal rod which conducts heat well so she was burnt. The woman on the right is holding a wooden stick that does not conduct heat well so she was not burnt.

6. When any material is heated, its molecules start to move more quickly and forcefully. The collisions of all these molecules causes the material to _________. This happens with all matter, but is most obvious with gases. As they expand, they become _______________. expand less dense Convection When heat is moved because something warm is moving, then the heat is being transferred by convection. Here you see convection occurring over a fire. Warmed air expands and become less dense. Cooler, more dense nearby rushes underneath the warmer air and causes it to lift. As the warmed air rises, it cools and becomes more dense. As its density increases, it starts to sink to complete a cycle. Convection also occurs in liquids like this pot of boiling water. However, water does not have to boil to cause convection. It just has to become warmer in spots. also called convection current or cell; circular (cyclical) motion caused by density differences due to uneven heating Convection Cycle: ___________________________________________ __________________________________________________________

7. Humidity is ________________________________________________ the amount of water vapor in the air Directly related to measuring humidity is the Dew Point Temperature, which is the temperature where the air is ______________ (where the air __________________________________________________________) saturated is holding as much water vapor as possible Relative Humidity is ________________________________________ __________________________________________________________ and can range from ______ to ______. the percent of saturation of the air; ratio between actual amount of water vapor in the air/air’s capacity at that temperature 0% 100% Low relative humidity means _________________ conditions, while a High relative humidity means ______________ conditions. dry, clear and sunny wet or cloudy Dew Point and Relative Humidity are directly related. When the relative humidity reaches ______, you have reached the dew point. The temperature where you reach 100% is called the Dew Point Temperature. This is the point in temperature where clouds, fog and dew form. 100%

8. As the temperature increases, the air __________ and it is capable of holding ______ water vapor. As a result, the relative humidity _________ as the temperature increases. The Dew Point temperature does not change. expands more decreases shrinks As the temperature decreases, the air __________ and it is capable of holding ______ water vapor. As a result, the relative humidity _________ as the temperature decreases. Again, the Dew Point temperature does not change. less increases Dew point and Relative Humidity are determined using an instrument called a ____________________ which contains both a wet-bulb and dry-bulb thermometer. Once the wet-bulb and dry-bulb temperatures are determined, the dew point and relative humidity can be determined by using the charts on page 12 of the ESRT. sling psychrometer

9. Air Pressure is _____________________________________________ __________________________________________________________ caused by the density of air and its resultant weight due to the pull of gravity on its molecules; greatest at low altitude It is measured either with units of ____________ or ________________. millibars inches of Mercury Both of these unit scales are found on page 13 of the ESRT. Weather maps always use air pressure to indicate where good and bad weather is. Low air pressure means _____________________________________ cloudy or rainy/snowy weather due to lifting air High air pressure means ______________________________________ clear and dry weather due to sinking air Lines of equal pressure are called ___________. Instruments used to measure air pressure are ___________________, _________________, or _________________. isobars aneroid barometers mercury barometers barographs Wind is caused by _________________________. The stronger the difference, the stronger the wind. On a weather map, the closer the isobars, the _________ the wind!!! differences in air pressure stronger Winds always move from _____ pressure to _____ pressure. high low

10. anemometer A ________________ measures the wind direction. An ____________ measures wind speed. Wind direction is always reported as __________ ____________________________. wind vane the direction the wind is coming from WEATHER VARIABLE RELATIONSHIPS Temperature: ________________ with increasing altitude. ________________ with increasing pressure. Holds ________________ water vapor as it gets warmer. decreases increases more Pressure: ________________ with increasing altitude. ________________ with increasing temperature. ________________ as water vapor increases. decreases increases decreases

11. Moisture (Water Vapor): ________________ with increasing altitude. ________________ with increasing temperature. ________________ with increasing air pressure. decreases increases decreases Temperature and Dew Point: As temperature and dew point get closer together, there is an _________ of clouds and precipitation. increase As they get further apart, there is ______________________________. decrease of clouds and precipitation Winds: For the northern hemisphere, winds blowing out of a __________ direction generally indicate stormy weather. Winds blowing from a ________ direction generally indicate fair weather. southerly northerly Remember, the stronger the wind, the stronger the difference between low and high pressure (which means the isobars are _______________.) closer together

12. B. STATION MODELS The National Weather Service produces map of surface conditions from across the country every hour of the day. These maps are compiled from Station Model data. These models represent _________________ and ______________ at the station (airport) listed by a three-letter identifier. Looking at one station model, it will contain the following information. weather conditions surface data Amount of cloud cover (as a percentage) 1) ______________________________________________ 2) ______________________________________________ 3) ______________________________________________ 4) ______________________________________________ 5) ______________________________________________ 6) ______________________________________________ 7) ______________________________________________ 8) ______________________________________________ 9) ______________________________________________ 10) ______________________________________________ Wind direction (by compass direction) Wind speed (in knots) Air temperature (degrees Fahrenheit) Dew Point (degrees Fahrenheit) Present weather conditions/precipitation Visibility (miles) Barometric pressure (in millibars) Pressure trend/change in air pressure over last 3 hours (mb) Precipitation in last 6 hours (inches of rain)

13. All of this information is located in and around the station model, which just starts as an open circle and then is filled in with data. Below is a sample station model and present weather symbols that could appear with the station model. The information is taken directly from the ESRT. Meteorologists try to save room on the station models, so everything is shortened as much as possible. The trickiest variable to read is air pressure. Here is the simple conversion. put a “10” in front of the number and place a decimal point before the last digit If the station model air pressure number is less than 500 mb, _________ __________________________________________________________. If the station model air pressure number is greater than 500 mb, _______ __________________________________________________________. put a “9” in front of the number and place a decimal point before the last digit

14. If you want to change recorded air pressure to the coded form on the station model, just simply _____________________________________. drop of the “9” or “10” and the decimal point C. MOISTURE AND ENERGY TRANSFER Water changes its form from solid to liquid to gas and back again. This transformation is called a change of state. Whenever water or any other material changes state, energy in the form of heat is either absorbed or released as part of the process.

15. Condensation: _____________________________________________ __________________________________________________________. change of phase from water vapor to liquid water, occurs when air cools and the temperature drops to the dew point This is the opposite of evaporation. CondensationNuclei: ________________________________________ __________________________________________________________ __________________________________________________________. tiny particles that water droplets form on (salt, dust, pollen); without nuclei, water droplets cannot condense; air can cool below the dew point without condensation (called supercooled air) If the temperature drops to the dew point temperature and condensation nuclei are present, condensation will occur. Condensation of liquid water when air cools to DP above 32oF/0oC Dew: _____________________________________________________ Frost: ____________________________________________________ Deposition of ice crystals when air cools to DP below 32oF 0oC Clouds:____________________________________________________ __________________________________________________________. Condensation of water or deposition of snow in the air from expansion and cooling of rising air to the dew point There are three basic types of clouds __________, ________, and __________ from which all clouds get their names. cirrus cumulus stratus

16. Cloud Formation expands As air is heated, it ______. Because it becomes __________ as it expands, it is pushed upwards by more dense surrounding air rushing underneath it. Being larger in size, the packet of air can now also absorb and hold ______ water vapor. less dense Smoke rising along with heated air molecules more As the warm, moist air packet is lifted, it ______. When it cools to the point where its temperature reaches the dew point, its water vapor starts to _________ out into tiny water particles. These water droplets clump together and form clouds cools condense Water condensing on outside of glass. This happens because the warm air surrounding the glass cools when it comes into contact with the glass. Once it cools to the dew point, water vapor condenses out into water droplets.

17. Condensation Lifting and Cooling Expansion Heating Precipitation: ______________________________________________ solid or liquid water falling from the sky There are five basic types of precipitation: 1. Snow: ____________________________________________ 2. Rain: ____________________________________________ 3. Sleet: ____________________________________________ 4. Freezing Rain: _____________________________________ 5. Hail: _____________________________________________ Ice crystals in a cloud remain solid to the ground Snow melts and liquids remain liquid to the ground Rain freezes on its way down to the ground Rain freezes once it hits the frozen ground Rain/ice cycles through a storm cloud growing larger

18. Air is pushed up and over a mountain. As it rises, it cools and water condenses out and precipitates. As the now dry air crosses the mountain and descends, it is dry and heats as it is compressed. Orographic Effect: _________________________________________ __________________________________________________________ __________________________________________________________ Rain Shadow: _____________________________________________ __________________________________________________________ Dry (desert) area on the downwind side of a mountain range due to orographic effect on windward side of the mountain range

19. Moisture and Energy Input: Moisture is added to the atmosphere from Earth through two processes. They are: Evaporation: _______________________________________________ Water changes to water vapor due to energy input (heating) Transpiration:_______________________________________________ Water given off by plants These two terms are combined into one and called __________________ evapotranspiration The rate of evapotranspiration depends on three things: 1. __________________________________________________ 2. __________________________________________________ 3. __________________________________________________ Amount of energy available (temperature) Surface area of water sources Moisture content of the air (relative humidity/vapor pressure)

20. Specific Heat: ______________________________________________ __________________________________________________________ amount of heat energy required to raise the temperature of one gram of material one degree Celsius The higher the specific heat of a material, _________________________ __________________________________________________________ the more energy required to heat a material and the longer it will take to heat up or cool down The lower the specific heat of a material, _________________________ __________________________________________________________ the less energy required to heat a material and the quicker it will take to heat up or cool down A good example of a material with a low specific heat is most metals. Because they have a low specific heat, they will get hot very quickly. Think of an automobile hood in the summer. water ________________ has the highest specific heat capacity among all the naturally occurring materials on Earth (1.0 calories/gram oC). Specific heats of some common materials are listed on Page 1 of the ESRT.

21. Latent Heat Water exists in our environment as solid, liquid and gas. In each form, water has the ability to store a lot of heat energy without its temperature changing. This stored heat is called _______________. Latent heat is _______________________________________________. When a phase change (going from one form to another) occurs, _____ _____________________________ until the water has collected or released its full amount of latent heat.. latent heat potential energy (stored energy waiting to be used) the temperature DOES NOT change The heat energy is either absorbed or released, increasing or decreasing the _______________ of the molecules. potential energy When a phase change is NOT occurring, the temperature WILL change as heat energy is absorbed or released.

22. Latent Heat of Water Melting occurs when ________________________________________. Freezing occurs when ______________________________. The latent heat required for these changes is _______________ of water and is called the ____________________. (See Page 1 of the ESRT.) Latent heat is the amount of energy that needs to be absorbed or given off before the water molecules change state. ice changes to liquid water liquid water changes to ice 80 calories/gram Heat of Fusion of water Evaporation occurs when ____________________________________. Condensation occurs when ______________________________. The latent heat required for these changes is _______________ of water and is called the ____________________. (See Page 1 of the ESRT.) liquid water changes to water vapor water vapor changes to liquid water 540 calories/gram Heat of Vaporization How does the latent heat of fusion compare to the latent heat of vaporization for water? _______________________________________ It is much less.

23. It takes much less energy exchange for freezing/melting to occur than for evaporation/condensation. What does this mean? ________________________________________ __________________________________________________________. Example: Liquid water cools in temperature until it reaches the freezing point. Once it reaches the freezing/melting point it must lose _____ calories for every gram of water present before the liquid water will start to freeze. The temperature will not change until this heat of fusion is lost. Just the opposite must happen for ice to melt. 80oC/g

24. Energy (heat) is transferred in our atmosphere in one of three ways: _______________, ________________, and ______________. radiation conduction convection ____________from the sun strikes the ground and warms it. Very little radiation actually heats the air. Radiation Heat is _____________from the ground to the air molecules that actually touch Earth’s surface. It only heats those molecules in direct contact with the ground. conducted _____________ is the main method that conducts heat through gases like our atmosphere. Convection is driven by differences in _________. Air that is warmed _________ and becomes less dense. Cooler air is more dense and pushes down underneath the warmer air. The warmer air thus _________, carrying its heat energy with it. This upward movement of warmer air and downward movement of cooler air creates what is called a _____________________. Convection density expands rises convection current or cell

25. Flying animals know about convection cells. Hawks and other soaring birds look for these upward moving currents of air. That is what allows them to soar through the air, rising upward without even flapping their wings. ______________ and _______________ like those found at the beach are simple examples of convection cells that can operate in two different directions depending on the relative heating of Earth’s surface. Sea breezes land breezes Land heats up faster than water, so during the day, air over land rises creating a sea breeze. At night, the land cools more quickly than water, so the air over the water is relatively warmer and air rises over the water.

26. D. PLANETARY WINDS/AIR MASSES/FRONTS PLANETARY WINDS Pressure Belts: _____________________________________________ _________________________________________________. Checking the diagram below and Page 14 of the ESRT, we can see where high pressure (therefore _____) and low pressure (therefore _____) belts are located on the surface of Earth. large areas of high or low pressure due to convection caused by unequal heating of Earth surfaces dry wet Where air converges and rises, _______________ results. These regions are known as ____________________. low pressure Zones of Convergence Where air sinks and diverges, ________________ results. These regions are known as _____________________. high pressure Zones of Divergence

27. Planetary wind patterns area caused by: __________________________________________________ __________________________________________________ Air movement from zones of divergence to zones of convergence Coriolis Effect These basic wind patterns can be altered slightly by the factors listed below. _______________________________ _______________________________ _______________________________ Altitude Position relative to mountains Position relative to large bodies of water

28. There may also be a seasonal shift in the winds over a particular area, called a ___________. These are caused by a change in where the direct rays of the sun are striking Earth as well as the location of land masses and oceans. monsoon This happens in many parts of the world (including the U.S.) but most notably in southeast Asia. The diagram below shows these monsoons. In winter, the air flows from the __________________. This means ____ weather. In summer, the air flows from the _____________. This means ______ weather. land mass (north) dry ocean (south) wet

29. Another example of a seasonal change in weather patterns is called ________. A change in water circulation patterns off the coast of South America has implications for weather across the world. El Nino Normally, easterly winds off the coast of South America push surface ocean waters away from the continent. This allows cooler deep water to well up and keeps the air temperatures cooler in that location. If winds weaken, upwelling decreases, allowing surface temperatures to change across the Pacific Ocean. This, in turn, affects weather patterns across the globe.

31. This is the normal pattern of winds approaching the United States in the winter. Because of El Nino, westerly winds are pushed further north than is normal. As a result, the southern United States experiences cooler, wetter winters than normal. Other parts of North America are drier and warmer.

32. AIR MASSES An Air Mass is a ____________________________________________ ____________________________. These air masses are named depending on the weather characteristics in their geographic region of origin. This region is called a ________________. On a weather map, air masses are identified by their source region. Since they are based on their temperature and humidity characteristics, their names reflect this. large body of air having uniform characteristics like temperature and moisture content source region Looking at moisture, if the air mass formed over land, it is _____ and called _____________. If it formed over an ocean, it is _____ and called _______________. dry continental wet maritime Looking at temperature, if the air mass formed in the tropics, it is called _____________. If it formed near the equator, it is called _______________. If it formed over high latitudes, it is called ________. If it formed near the poles, it is called _______________. tropical arctic equatorial polar

33. Meteorologists use lower case letters ___ and ___ to represent maritime and continental conditions respectively and the capital letters ___, ___, ___, and ____ to represent tropical, equatorial, arctic and polar air masses respectively. m c T e A P Air mass names and symbols can be found on Page 13 of the ESRT. The map to the right shows where these air masses originate for North America.

34. Related to air masses are air pressure systems. There are two types. High (Anticyclone): ____________________________________ __________________________________________________________ ___________________________. On a weather map, their appearance and wind circulation would look like the diagram below. high pressure air mass that spins CLOCKWISE, spiraling outward away from the center; associated with clear, cool weather Low (Cyclone): ____________________________________ __________________________________________________________ ___________________________. On a weather map, their appearance and wind circulation would look like the diagram below. low pressure air mass that spins COUNTER-CLOCKWISE, spiraling inward toward the center; associated with cloudy, wet or stormy weather Diagram by Steve Kluge

35. The circulating pattern of the high and low pressure systems is due to the _______________________ which makes everything turn to the right in the northern hemisphere. Coriolis Effect Air always flows out of ______ pressure systems and into ______. high lows In other words, just like flowing water or a falling object , air always moves from ______ to ______. high low Remember: High clock on the wall down to the low counter. FRONTS A Front is: _________________________________________________ ____________________________. They are always attached to a _____ __________system and move counter-clockwise around it. They are the main source of precipitation. a boundary or interface between two air masses with different characteristics low pressure There are four types of fronts, all named because of their movement and what type of air is pushing the other out of the way.

36. forms when warm air meets and slowly glides up and over the back of a cold air mass. Warm fronts generally cause steady, gentler precipitation forms when cold/cool air overtakes warmer air and shoves its way underneath warmer air, lifting it. Cold fronts cause brief but heavy precipitation.

37. Notice the narrow line of intense rain along the cold front in New England.

38. cold front overtakes a cool air mass and the two air masses together force up warmer air. Occluded fronts can cause heavy precipitation. The boundary between two air masses is stagnant (not moving). Stationary Front: ____________________________________________ ________________________________________. The weather of these fronts most closely resembles warm front weather conditions, although there is usually just drizzle and no moderate or heavy precipitation. Map Symbol: Reminder: The map symbols for all four weather fronts can be found on Page 13 of the ESRT.

39. E. WEATHER FORECASTING Meteorologist: ______________________________________________ Forecasting the weather involves putting together all of the pieces we’ve learned so far. We need to analyze the data and interpret what that data are telling us, then use forecasting skills to make the right predictions. scientist who studies and forecasts weather Field Values: _______________________________________________ __________________________________________________________ such as temperature, air pressure, relative humidity and dew point shown on weather maps with isolines Isolines: ___________________________________________________ Lines connecting points having equal field values Isotherms: __________________________________ Isobars: ____________________________________ lines connecting points of equal temperature lines connecting points of equal air pressure

40. Gradient: __________________________________________________ Change in value from one point to another An example of gradient is how steep a hill is, i.e., how much does its altitude change over a given distance? The formula to calculate gradient is on the front cover of the ESRT. The two types of gradient we normally look at in weather are ____________________and _______________________. They are both calculated in the same way. temperature barometric pressure You find the difference in field value (either temperature or pressure) and divide that number by the distance (from the scale on the map in either kilometers or miles). You can easily determine temperature and pressure gradients on weather maps. If the isolines are close together, that indicates a ______ gradient. If they are widely spaced apart, then you have a ____________ gradient. steep shallow IMPORTANT: The pressure gradient is directly related to __________. wind speed The closer the isobars are to each other, the _______ the wind speed! faster

41. Synoptic Weather Map _______________________________________. Gives a “bird’s eye” view of the weather The map below represents a typical synoptic weather map showing two cyclones and one anticyclone with isobars and fronts. The weather map below is a commercial map for nonscientists, but it shows lows (cyclones) and highs (anticyclones) along with their associated fronts.

42. Forecasters generally watch the direction a cyclone has been moving and assume the system will continue to move in that direction and at roughly the same speed. This is called the ________________. This can be calculated by measuring the distance the storm has traveled and dividing that distance by the time it took to go that far. storm track northeast or southeast Over North America, storms generally travel ______________________ because the prevailing winds blow from ______ to ______. west east They are steered by the Jet Stream _____________________________ that can travel as fast as ________________. strong winds in upper troposphere 300 km/hr Modern day meteorologists use _______________________, _________ __________, ____________________, and ________________ to attempt to forecast the weather. They are relatively accurate in day to day forecasting, but because there are so many variables involved, long range forecasting tends to be less accurate. weather instruments past weather data weather satellites computer analysis

43. KEY FEATURES OF WEATHER MAPS • ___________________________________ • ___________________________________ • ___________________________________ • ___________________________________ • ___________________________________ Station models Cyclones (low pressure systems) Anticyclones (high pressure systems) Fronts Isolines (normally isobars)

44. F. SEVERE STORMS (THUNDERSTORMS/TORNADOES/HURRICANES/WINTER STORMS) Thunderstorm: ( )________________________________ ________________________. Lightning, flooding from heavy rain, hail, damaging winds and tornadoes are all possible from strong or severe thunderstorms. form where moist, unstable air is forced upward abruptly most common powerful but small tower of swirling winds that form within a thunderstorm Tornado: ( )_____________________________________ ____________________________. Their distinct funnel shape makes them easy to recognize. The center of a tornado is called the _________. Winds inside the vortex can reach speeds higher than _______________! most violent vortex 600 km/hr FujitaScale: describes ___________ and possible damage associated with different strength tornadoes. F-0 is the __________ tornado and F-5 is the __________. Tornadoes can be anywhere from _________ to ________ wide and can travel at a forward speeds of _______________. intensity weakest meters strongest 40 – 60 km/hr a mile

45. Tornadoes have occurred in almost every state in the country but are most common in the ______________________ where ______ air masses from the south and _______ air masses from the north collide. center of the country warm cooler Hurricane: ( )____________________________ _____________________________________________. Hurricanes go through life-cycles, starting as ___________________, then become __________________, and finally become ____________. Their designation is dependent on their top wind speed. form in low latitudes over warm waters; energy released by condensation fuels the storm largest/400 miles across tropical depressions tropical storms hurricanes Saffir-Simpson Scale: Hurricanes are ranked on this scale from 1 to 5 with 1 being the _________ hurricane and 5 being the ___________. The scale is based on ____________, ______________ and __________ ________ produced by the storm. strongest weakest wind speed air pressure wave heights Hurricanes normally have an _______ at their center which is an area of surprisingly clear and calm weather. The clouds surrounding the eye, however, called the __________ are where the winds are the strongest. eye eye wall

46. Hurricane Francis – September 2004

47. Hurricane Isabel showing isobars. Hurricane Ivan: Tightly packed isobars indicate strong winds.

48. Hurricanes are very intense low pressure centers. Like mid-latitude cyclones, winds circulate in a _________________ direction around the eye. counterclockwise Hurricanes form over warm, tropical ocean waters. In order for a hurricane to form, the water temperature must be above _____ and water depth must exceed ____________. A hurricane gets its energy and strength from the __________________ stored in the warm ocean water. 80oF 70 meters latent heat Once hurricanes reach land, they are cut off from their energy supply and they quickly ________________. The ___________ and ___________ of the United States are the areas most commonly affected by full-strength hurricanes. However, hurricanes have struck the coast of New York and we often experience the remnants of hurricanes that have made landfall elsewhere. lose strength Gulf Coast southeast coast The greatest risk from hurricanes is the _____________. Other damage results from _______________, _______________, and ____________. storm surge high winds heavy rains tornadoes

49. WinterStorms: ____________________________________________ ____________________________________________. The greatest risk from winter storms are _____________, ______________________, and ______________. There are two unique types of winter storms important to people in New York. low pressure systems bring together dry, cold, northern air and warmer, moisture-laden southern air heavy snow very cold temperatures high winds intensified Lake Effect Storm: snowfall at a specific location is ______________ because of its nearness to a large body of water. As cold air passes over a large body of relatively warmer water, the air ______ and picks up moisture. Once the air moves past the water body, it ______ once more. No longer able to carry the moisture, it is dropped in the form of snow. warms cools Lake effect snow storms are localized events. Only areas ____________ from and relatively ______ to the water body are effected by lake effect. downwind close See diagram on next page. low pressure system moving up Atlantic coast, causing northeast winds that carry a lot of moisture in off from the Atlantic Ocean; more intense closer to the ocean Nor-easter: slang term or local name for _________________________ __________________________________________________________ __________________________________________________________

50. LAKE EFFECT SNOW