Download Meteorology A. Air Pressure 1. Air pressure – the

Meteorology A. Air Pressure 1. Air pressure – the weight of air pressing down on Earth 2. temperature and altitude determine air pressure 3. the more air particles are present, the more air density or pressure exists 4. the less air particles are present, the less air density or pressure exists 5. High pressure a. air is more dense b. associated with cold air (more dense than warm air) c. associated with sinking air 6. Low pressure a. air is less dense b. associated with warm air (less dense than cold air) c. associated with rising air 7. warm air rises, cold air sinks 8. air cools as it rises 9. air pressure is measured using a tool called a barometer 10. winds are formed when air from a high pressure (more dense) moves to areas of low pressure (less dense) B. Air Mass 1.air mass – large mass of air that takes on the temperature and moisture characteristics of the surface below it 2. air moves from an area of high pressure (more dense) to areas of lower pressure (less dense) 3. a high pressure system a. rotating mass of cool, dry air rotating in a downward clockwise motion b. creates sunny and pleasant weather 4. a low pressure system a. rotating mass of warm, moist air rotating an upward counterclockwise motion b. creates stormy, windy weather 5. air masses are classified by their temperature and humidity (moist or dry) 6. air masses in the US move west to east C. Fronts 1. there are 4 major air masses that effect the weather in North America a. continental polar (cP) b. continental tropical (cT) c. maritime polar (mP) d. maritime tropical (mT) 2. most weather occurs along the border of these air masses at boundaries called fronts 3. Cold front a. occurs when a cold air mass overtakes a warm air mass b. this pushes the warm air mass upward c. creates severe weather lasting a short period of time d. represented by blue triangles on a weather map 4. Warm front a. occurs when a warm air mass slides up and over a cold air mass b. this creates rainy weather that lasts for several days c. represented by red semicircles on a weather map 5. Stationary front a. occurs when a cold and warm air mass meet but do not move in either direction b. this creates sluggish winds and precipitation c. represented by alternating blue triangles and red semicircles 6. Occluded front a. occurs when two cold air masses merge and force warmer air between them to rise b. this creates high winds and heavy precipitations c. represented by purple alternating triangles and semicircles D. Clouds 1. cloud – a visible mass of condensed water in the atmosphere made up of mixtures of tiny droplets of water or tiny crystals of ice 2. form when water evaporates from Earth’s surface 3. classified according to shape and altitude 4. prefixes: a. cirro – describes high clouds (above 6000m) b. alto – describes middle clouds (between 2000m and 6000m) c. strato – describes low clouds (below 2000m) E. Types of Clouds 1. cirrus a. high, white, feathery cloud b. usually associated with fair weather 2. cumulus a. thick, puffy masses b. usually associated with fair weather 3. stratus a. occurs in layers and often cover the whole sky b. usually associated with fair weather 4. nimbus a. dark, grey clouds with ragged edges b. associated with precipitation F. Fronts and Clouds 1. cold front – cumulonimbus clouds are large puffy rain clouds associated with severe thunderstorms along a cold front 2. warm front – cirrus, stratus, and nimbostratus clouds are associated with the passing of a warm front G. Water Vapor 1. humidity – the amount of water vapor in the air 2. relative humidity – ratio of water vapor in a volume of air relative to how much water vapor that volume of air is capable of holding a. warm air is capable of holding more moisture than cool air b. if you increased the temperature of a room without adding more moisture, the relative humidity of the room would decrease c. relative humidity is expressed as a percentage d. measured by a hygrometer 3. saturation – point at which the air holds as much water vapor as it possibly can a. warm saturated air contains more water vapor than cold saturated air 4. dew point – temperature to which air must be cooled at the same pressure to reach saturation a. if the same air continued to cool past the dew point, the air’s excess water vapor would condense to lead to precipitation 5. condensation (gas to a liquid) occurs only when air is saturated a. this leads to precipitation (rain, snow, freezing rain (glaze), sleet, hail) 6. saturation, relative humidity, and dew point are used to measure humidity Atmosphere and Climate A. Earth’s Atmosphere 1. atmosphere is composed of the following : a. Nitrogen (71%) b. Oxygen (28%) c. trace gases (1%) – argon, methane, hydrogen, and helium 2. atmosphere also contains ozone (O​3​) which absorbs UV radiation B. 5 Layers of the Atmosphere 1. Troposphere a. layer closest to Earth’s surface b. where most weather takes place and most air pollution collects c. temperature decreases with altitude 2. Stratosphere a. layer made primarily of ozone b. where jet stream is located c. temperature increases with altitude due to absorption of UV radiation 3. Mesosphere a. where most meteoroids are burnt up as they enter our atmosphere b. temperature decreases with altitude 4. Thermosphere a. layer where radio waves are transmitted b. where space shuttles are found c. ionosphere is located here – a layer of charged ions that cause Aurora Borealis and Aurora Australis at poles
d. temperature increases with altitude due to solar radiation 5. Exosphere a. outermost layer where satellites can be found b. temperature in this layer decreases with lower air pressure C. Climate and Weather 1. weather is the condition of the atmosphere over a short period of time 2. climate is the average daily weather for an extended period of time at a certain location 3. temperature and precipitation determine climate 4. factors that affect climate a. latitude b. elevation c. topography d. water bodies e. atmospheric circulation f. vegetation D. Climate 1. The Köppen Climate Classification System – organizes the world’s climates into categories based on the annual and monthly averages of temperature and precipitation 2. 3 major climate zones based: a. polar – coldest with temperatures below freezing b. temperate – more moderate temperatures and rainfall year­round c. tropical – warmest average temperatures with the most precipitation E. Natural Processes that Change Climate 1. El Niño a. associated with a band of warm ocean water temperatures that periodically develops off the Pacific coast of South America b. happens every 2 to 7 years and can last from 9 months to 2 years c. in South America, this leads to i. increased temperatures and rainfall d. in North America, this leads to i. mostly drier and warmer conditions e. effects both fishing and farming industries 2. La Niña a. climate pattern represented by the cooling of the eastern tropical Pacific Oceans b. in South America, this leads to i. in some areas, drought ii. in other areas, excessive rainfall, leading to flooding c. in North America, this leads to i. above average rainfall in the northern regions ii. below average rainfall in the southern regions iii. allows for more stronger­than­average hurricanes off the Atlantic andlessin the Pacific d. effects both fishing and farming industries 3. Volcanic eruptions a. increases the amount of solar radiation that is reflected back into space, decreasing the temperature of the atmosphere 4. Sunspots
a. sunspot – dark blemishes that appear with the sun is most intense (active) b. associated with increased temperatures in Europe and North America c. when sun is less intense (active), there is a decrease temperatures 5. Earth’s orbit a. Earth’s orbit around the sun is elliptical, which can bring the Earth closer to the sun, warming the Earth 6. Earth’s tilt a. the angle of the tilt varies which changes the severity of the seasons 7. Carbon dioxide a. atmosphere CO​2​ has increased by almost 40% since pre­industrial times b. this increase in CO​2​ has increased global temperatures by absorbing heat from the sun F. Greenhouse Effect 1. greenhouse effect – natural warming of Earth and it’s atmosphere 2. when sunlight reaches Earth’s surface, it can either be reflected back into space or absorbed by Earth 3. greenhouse gases – gas that absorbs and releases radiation 4. examples of greenhouse gases include a. water vapor (H​2​O) b. carbon dioxide (CO​2​) c. methane (CH​4​) d. nitrous oxide (NO) 5. greenhouse gases lead to the greenhouse effect by acting like a blanket, trapping sun’s heat close to the Earth’s surface 6. CO​2​ is the primary greenhouse gas that contributes to climate change a. it is released by animals and plants through respiration b. also released by burning of fossil fuels by humans c. deforestation (clearing land) for agriculture, industry, and urbanization have also increased CO​2​ concentrations 7. warmer conditions can lead to more evaporation and precipitation 8. a stronger greenhouse effect will warm the oceans and partially melt glaciers and other ice, increasing the sea level G. Global Temperatures 1. increased temperatures will cause drought conditions effecting agriculture 2. species that are able to adapt more quickly to increased temperatures and rapid temperature changes will become more abundant 3. loss of biodiversity in ecosystems will be widespread and species diversity will decline 4. increased global temperatures raise sea levels worldwide H. Heat Islands 1. heat islands – a metropolitan areas that is significantly warmer than surrounding areas due to human activity 2. open air and vegetation is replaced by urbanization 3. increases energy demands, air conditioning costs, air pollution, greenhouse gas emission, heat­related illness and mortality, and water quality 4. to reduce heat island effect : a. plant trees and vegetation b. using eco­friendly building materials I. Land Use 1. urbanization­ increasing the number of people that live in urban areas a. closely linked with modernization and industrialization b. results in heat islands 2. deforestation – removal of trees in a forest for the conversion of farms, ranches, or urban use a. trees are sold or land is used for human purposes b. deforestation without sufficient reforestation has resulted in the loss of habitats and biodiversity 3. agriculture – cultivation of animals and plants for food, fuel, or medicines to sustain human life a. leads to loss of natural habitats Storms A. Wind Patterns 1. Coriolis effect – wind (moving air) is deflected to the right in the northern hemisphere and to the left in the southern hemisphere 2. trade winds a. air sinks, warms, and moves toward the equator in a westerly direction b. at the equator, the air rises again and moves back to 30​o​ where is sinks and starts the process all over again c. occurs at 30​o​ north and south latitude 3. prevailing westerlies a. surface winds move towards the poles in an easterly direction b. occurs between 30​o​ and 60​o​ north and south latitude 4. polar easterlies a. flow from the northeast to the southwest in the northern hemisphere b. wind flow is reversed in the southern hemisphere c. characterized by cold air d. occurs between 60​o​ latitude and the poles
5. jet streams – narrow bands of fast, high­altitude westerly winds a. can flow up to 185 km/h at elevations of 10.7 to 12.2 km B. Predicting Storms 1. Doppler Effect – is the change in wave frequency that occurs in sound or light as the energy moves towards or away from the observer 2. meteorologists use Doppler radar to plot the speed at which raindrops move toward or away from a radar station 3. because moving rain drops are caused by wind, it provides a good estimation of wind speed associated with precipitation C. Hurricanes (Tropical cyclones) 1. large, rotating, low pressure storm 2. aka tropical cyclone 3. thrive on the tremendous amount of energy in warm, tropical oceans 4. as water evaporates from the ocean surface, heat is stored which is later released when the air begins to rise and water vapor condenses into clouds and rain 5. the rising air creates an area of low pressure at the ocean surface 6. as more warm air moves toward the low pressure center to replace the air that has risen, the Coriolis effect causes the moving air to turn counterclockwise in the northern hemisphere which produces the cyclonic rotation (Before and After pictures from hurricane Ike in 2008 over Texas) Hurricane Precautions: ● Prepare enough water and food for several days. ● Fill tank of car with gas and take out cash. ● Seek shelter in a secure structure that will withstand strong winds. ● Move to an area away from storm surge. ● Stay away from windows and doors during the storm and do not go outside. ● Close all interior doors and go to an interior first floor room such as a bathroom or a closet ● Lie on the floor under a table D. Thunderstorms 1. a storm with thundering and lightning and typically with heavy rain 2. lightning is electricity caused by the rapid rush of air in a cumulonimbus cloud which separates electrons and causes an electrical imbalance 3. caused by: a. abundant moisture in the atmosphere b. rising of air so that the moisture can condense which releases heat c. air must continue to cool for the growing cloud to stay warmer than the surrounding air which causes instability in the atmosphere 4. supercell – self­sustaining, extremely powerful storm Thunderstorm Precautions ● The best defense against thunderstorms is to stay inside a sturdy building or shelter that can protect you from deadly lightning, large hail, damaging winds, flooding rain and tornadoes. ● Once in a shelter, stay away from windows and avoid electrical equipment and plumbing. Remember to bring pets inside. If there is time, secure loose objects outside as these objects often become dangerous flying debris in high winds. ● Avoid open spaces, isolated objects, high ground and metallic objects. ● Get out of boats and away from bodies of water. Remember, if you can hear thunder, you are close enough to the storm to be struck by lightning​. E. Tornados 1. a violent, whirling column of air in contact with the ground 2. typically associated with supercells 3. forms when wind speed and direction change suddenly with height Tornado Precautions ● Prepare for tornadoes by gathering emergency supplies including food, water, medications, batteries, flashlights, important documents, road maps, and a full tank of gasoline. ● When a tornado approaches, take shelter indoors—preferably in a basement or an interior first­floor room or hallway. ● Avoid windows and seek additional protection by getting underneath large, solid pieces of furniture. ● Avoid automobiles and mobile homes, which provide almost no protection from tornadoes. ● Those caught outside should lie flat in a depression or on other low ground and wait for the storm to pass