GEOL 1301 Fall 2014 Lecture 19Outline of Last Lecture I. Climate Systems (cont.)Outline of Current LectureII. Climate SystemsCLIMATEClimate classification[edit]There are several ways to classify climates into similar regimes. Originally, climes were defined in AncientGreece to describe the weather depending upon a location's latitude. Modern climate classification methods can be broadly divided into genetic methods, which focus on the causes of climate, and empiricmethods, which focus on the effects of climate. Examples of genetic classification include methods basedon the relative frequency of different air mass types or locations within synoptic weather disturbances. Examples of empiric classifications include climate zones defined by plant hardiness,[10] evapotranspiration,[11] or more generally the Köppen climate classification which was originally designed to identify the climates associated with certain biomes. A common shortcoming of these classification schemes is that they produce distinct boundaries between the zones they define, rather than the gradual transition of climate properties more common in nature.Bergeron and Spatial Synoptic[edit]Main article: Air massThe simplest classification is that involving air masses. The Bergeron classification is the most widely accepted form of air mass classification.[citation needed] Air mass classification involves three letters. The first letter describes its moisture properties, with c used for continental air masses (dry) and m for maritime air masses (moist). The second letter describes the thermal characteristic of its source region: Tfor tropical, P for polar, A for Arctic or Antarctic, M for monsoon, E for equatorial, and S for superior air These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.(dry air formed by significant downward motion in the atmosphere). The third letter is used to designate the stability of the atmosphere. If the air mass is colder than the ground below it, it is labeled k. If the airmass is warmer than the ground below it, it is labeled w.[12] While air mass identification was originally used in weather forecasting during the 1950s, climatologists began to establish synoptic climatologies based on this idea in 1973.[13]Based upon the Bergeron classification scheme is the Spatial Synoptic Classification system (SSC). There are six categories within the SSC scheme: Dry Polar (similar to continental polar), Dry Moderate (similar to maritime superior), Dry Tropical (similar to continental tropical), Moist Polar (similar to maritime polar), Moist Moderate (a hybrid between maritime polar and maritime tropical), and Moist Tropical (similar to maritime tropical, maritime monsoon, or maritime equatorial).[14]Köppen[edit]Monthly average surface temperatures from 1961–1990. This is an example of how climate varies with location and seasonMonthly global images from NASA Earth ObservatoryMain article: Köppen climate classificationThe Köppen classification depends on average monthly values of temperature and precipitation. The most commonly used form of the Köppen classification has five primary types labeled A through E. Theseprimary types are A, tropical; B, dry; C, mild mid-latitude; D, cold mid-latitude; and E, polar. The five primary classifications can be further divided into secondary classifications such as rain forest, monsoon, tropical savanna, humid subtropical, humid continental, oceanic climate, Mediterranean climate, steppe,subarctic climate, tundra, polar ice cap, and desert.Rain forests are characterized by high rainfall, with definitions setting minimum normal annual rainfall between 1,750 millimetres (69 in) and 2,000 millimetres (79 in). Mean monthly temperatures exceed 18 °C (64 °F) during all months of the year.[15]A monsoon is a seasonal prevailing wind which lasts for several months, ushering in a region's rainy season.[16] Regions within North America, South America, Sub-Saharan Africa, Australia and East Asia are monsoon regimes.[17]A tropical savanna is a grassland biome located in semiarid to semi-humid climate regions of subtropical and tropical latitudes, with average temperatures remain at or above 18 °C (64 °F) year round and rainfallbetween 750 millimetres (30 in) and 1,270 millimetres (50 in) a year. They are widespread on Africa, and are found in India, the northern parts of South America, Malaysia, and Australia.[18]The humid subtropical climate zone where winter rainfall (and sometimes snowfall) is associated with large storms that the westerlies steer from west to east. Most summer rainfall occurs during thunderstorms and from occasional tropical cyclones.[19] Humid subtropical climates lie on the east sidecontinents, roughly between latitudes 20° and 40° degrees away from the equator.[20]Humid continental climate, worldwideA humid continental climate is marked by variable weather patterns and a large seasonal temperature variance. Places with more than three months of average daily temperatures above 10 °C (50 °F) and a coldest month temperature below −3 °C (27 °F) and which do not meet the criteria for an arid or semiarid climate, are classified as continental.[21]An oceanic climate is typically found along the west coasts at the middle latitudes of all the world's continents, and in southeastern Australia, and is accompanied by plentiful precipitation year round.[22]The Mediterranean climate regime resembles the climate of the lands in the Mediterranean Basin, parts of western North America, parts of Western and South Australia, in southwestern South Africa and in parts of central Chile. The climate is characterized by hot, dry summers and cool, wet winters.[23]A steppe is a dry grassland with an annual temperature range in the summer of up to 40 °C (104 °F) and during the winter down to −40 °C (−40 °F).[24]A subarctic climate has little precipitation,[25] and monthly temperatures which are above 10 °C (50 °F) for one to three months of the year, with permafrost in large parts of the area due to the cold winters. Winters within subarctic climates usually include up to six months of temperatures averaging below 0 °C (32 °F).[26]Map of arctic tundraTundra occurs in the far Northern Hemisphere, north of the taiga belt, including vast areas of northern Russia and Canada.[27]A polar ice cap, or polar ice sheet, is a high-latitude region