What are Plant Hardiness Zones And Are They Really Creeping Northward? (Credit: USDA, The New York Times)
It was during the Great Depression that two researchers began creating maps to educate farmers on what crops could grow in their respective regions of the U.S. One researcher, Henry Skinner of the U.S. National Arboretum, began tailoring his map by separating the country into zones that were separated into increments of ten degrees Fahrenheit. Researchers Donald Wyman of the Arnold Arboretum began creating another map during the same time period that would split the U.S. into eight zones that could have temperature differences of either five, ten, or fifteen degrees.
It wasn’t until the 1960’s, however, that most agriculturalists adopted the U.S. National Arboretum map as the standard for gardening, despite the release of Wyman’s map in 1938. Wyman’s map was hard to follow since the zones were broad. This can cause trouble for gardeners in regions that may have diverse microclimates, something even the United State Department of Agriculture (USDA) acknowledges on their website. These microclimates can come in the form of urban heat islands, such as large cities like New York City and Los Angeles, where the overall average temperature may undergo less drastic diurnal temperature variations in comparison to surrounding areas. Areas like these will absorb more heat due to lower albedos and increased absorptivity of surfaces such as blacktop and concrete. This can cause for a warmer plant hardiness zone than areas just miles outside the typical city center, where factors such as more grassy surfaces and differences in elevation may cause a decrease in the overall average temperature, causing for a cooler plant hardiness zone.
It is once all of the aforementioned factors such as the characteristics of microclimates are taken into account that one can think about how those exact climates may be affected by an increase in temperature, as caused by climate change. A recent analysis by the National Oceanic and Atmospheric Administration, as reported in the New York Times, brought to light how increasing temperatures due to climate change already are and may continue to have an impact on the movement of plant hardiness zones northward.
The zones are currently based on the coldest temperature of the year at various locations across the U.S., averaged over a 30 year period. The USDA’s map was revised in 2012 after over twenty years without revisions. Although the perimeters of all plant hardiness zones did creep noticeably northward, it was noted in the Times article that it was impossible to distinguish the influence of climate change on this northward progression from other systematic differences given that the USDA changed their map-making process s between the 1990’s and 20212. In other words, the USDA map is broad and fails to take into account climate change, making it impossible to make future predictions based off of just plant hardiness.
This is why the researchers at NOAA created the maps using the thirty-year technique practiced by the USDA. These maps take into account the effects of greenhouse gas emissions on the climate that the USDA’s revised maps didn’t. The maps clearly show how by 2040 certain zones designated by NOAA will have creeped much farther northward, with areas like the New York City metro area being considered as Zone 8, the same hardiness as areas as far south as Montgomery, Alabama and central Georgia.
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©2019 Weather Forecaster Jacob Dolinger
Image Credit: BBC
Over the past few years, you’ve probably heard about climate change. And global warming. But what’s the difference? Is there even one? Why has the name seemingly changed? The use of both of these terms can be confusing, so let’s get them sorted out.
Global warming is the term that was originally most widely used to refer to the observed rapid changes in Earth’s climate system. It refers to the fact that overall, the planet is getting warmer. While there are some areas of the planet experiencing a cooling trend in their climate, the Earth as a whole is warming, even when these cooling pockets are taken into account. However, this warming is only a piece of the story of what is currently happening to our planet. Global warming is, in fact, a symptom of climate change.
The term “climate change” refers to the effects that global warming is having on the planet. The climate system involves more than just the temperature of the atmosphere. It also encompasses moisture in the atmosphere, and where and when it rains. Additionally, increasing global temperatures has a number of physical effects on the planet, such as melting land ice, sea level rise, and intensifying hurricanes, just to name a few. These, in turn, affect Earth’s climate. Thus, scientists use “climate change” to refer to all of the changes that are resulting and will result from increased global temperatures. Climate change is an umbrella term, under which global warming falls along with the other effects associated with an overall warming planet.
The media has shifted from global warming to climate change in their stories simply because “climate change” is a broader term that encompasses all changes and is more accurate if something like sea level rise or changing precipitation is being discussed. Scientists, however, have been using both terms for a long time. Each of these terms serves a different purpose for scientists in talking about what is happening to our planet. “Global warming” hones in on temperature changes, while “climate change” helps discuss other changes occurring in the Earth’s systems. While the two terms have been used interchangeably in public discourse and are closely related, it is important to remember the distinction between them.
©2019 Meteorologist Margaret Orr
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Image Source: https://www.bbc.com/news/science-environment-47144058
Spring is the season when severe weather kicks up again. In some areas, like the Central United States, it also means that tornado season will be starting up soon. And while this fact is common knowledge, the science behind why this season experiences such a noticeable uptick in severe weather events isn’t discussed as frequently. In this article, we will be exploring the key ingredients required for severe thunderstorms like supercells to form and how they come together at much greater rates during the spring months than at other times of the year in the mid-latitudes.
Ominous skies over eastern Colorado in May 2018.
The key ingredients for supercell thunderstorms are: instability, a source of lift, moisture, and wind shear. Instability refers to the general alterations of atmospheric stability. For instance, if you were to draw out a parcel of air, said parcel would rise, fall, or remain in its current location depending on how stable (or unstable) its surrounding environment was.
Source: Columbia University
The atmosphere can become more unstable via surface heating; whenever sunlight warms the ground, certain parcels at and near the surface will warm at a faster rate than their surrounding ones. It is these lighter, warmer parcels that will rise and will continue to do so until they enter a cooler environment. They themselves will then begin to cool and become heavier until they eventually sink back down to the surface where they can be heated up again and repeat this convective process.
Source: Columbia University
In order for storms to initiate, there must be a source of lift that allows for parcels of air to be vertically driven into the atmosphere. As such, the solar radiative heating that was recently described is one of many sources of lift that are available to prospective storms. If there is both sufficient heating and enough moisture over a localized area, then we can further expect for these parcels to vertically carry that water content along with them, leading to the vertical mixing of both heat and moisture across several layers of the atmosphere. These parcels will eventually condense and produce isolated showers and thunderstorms over those locations. Once they die, their outflow can help to produced localized areas of lift that can allow for a few more of these sorts of thunderstorms (oftentimes called garden-variety thunderstorms) to develop. These sorts of environments can be routinely found in tropical and subtropical areas such as Florida or the Caribbean, especially during the summer months. This makes spring unique for areas in the mid-latitudes in that it is around that season that plants and other forms of vegetation begin to grow and mature. In states such as Illinois and Indiana, which host large amounts of agricultural production, the added vegetation provides moist soil and added surface moisture content.
Source: Thomson Higher Education
That being said, these types of thunderstorms are almost never severe; once the environment runs out of surface moisture to mix into the atmosphere by the mid-to-late afternoon hours, then any storms that did develop will soon die out. In fact, these sorts of thunderstorms tend to have life expectancies of just under an hour. In order for storms to maintain themselves, they require another ingredient that has not yet been discussed.
We have already discussed one primary lifting mechanism: solar radiation. This process, however, only accounts for isolated thunderstorms to develop, given that such thunderstorms are limited to pockets where the air has become sufficiently unstable enough for parcels to rise and condense. If we take a look at North America, the return of spring re-introduces warmer air masses to the rest of the continent, while still experiencing cold spells whenever arctic air masses sink down into the lowe-48. The fronts that divide the two air masses themselves become large-scale lifting mechanisms that can also trigger thunderstorms. Moreover, geography also can play a significant role in providing sources of lift, as they are natural barriers that an air mass must overcome by rising on the wind side of the mountain before descending again on the leeward side. If the ascending air mass has sufficient moisture content and there is enough radiational heating, then the end-result can be oragraphically-induced thunderstorms.
Source: Thompson Higher Education
Starting around the start of spring, low-level moisture tends to also be advected (transported) from the Gulf of Mexico and into the Great Plains of North America. This introduction of moisture into the environment allows for any prospective storms to have a greater source of moisture than they otherwise would, aiding in the production of very sharp contrasts between moist and dry air masses. It is these sorts of boundaries between the two air masses that lead to the development of a dry line, which commonly develops in the Great Plains when this sort of moisture advection occurs. This area of the world also harbors a unique topographical setting which further allows for the production of dry lines; the elevation of the Great Plains gradually increases from east to west given they cover an area that’s stretches from the Mississippi River Basin all the way to the front-range of the Rocky Mountains. As such, when Gulf Moisture moves across the Great Plains, it slows down and fills in the areas which host lower elevations. As it does so, this air mass then comes in contact with much drier air from the American Southwest, which descends into the Great Plains from areas of higher elevation. Given that this drier, denser air mass, is descending into a moister, lighter air mass, the end result is a source of lift that can enable for much larger areas of ascent that can cover large swaths of the Plains on a much greater scale than what is observed from isolated, tropical and subtropical thunderstorms.
Source: Kendall/Hunt Publishing
We have already discussed three of the key ingredients that are required for severe thunderstorms: a source of lift, instability, and moisture. And as one would imagine, some of the most severe thunderstorms on the planet are a result of strong sources of lift, such dry lines. Nevertheless, the final ingredient required for supercells to initiate given that without it such a thunderstorm would not be able to maintain itself: wind shear.
Source: Earth Sky
Wind shear is essentially the change in wind speed and/or direction with respect to height. In the case of isolated thunderstorms that occur in the tropics, this ingredient is nearly non-existent given that the air masses of such environments tend to be stable with the exception of the localized areas of enhanced heating where the storms were able to initiate from. As such, once the thunderhead reaches its highest level in the atmosphere, all of the parcels that have cooled and condensed will sink back down to the surface. This downdraft will then cut off any supply of warm, moist air that initiated the thunderstorm, and produce an outflow boundary that may help to produce a new one in its wake. Under conditions in which there is greater wind shear, however, such a thunderstorm would have a downdraft that sinks further away from the core of the storm. As such, these thunderstorms require sources of lift that can produce sufficient enough wind shear given that this difference in the location between a thunderstorm’s updraft and downdraft will then in turn allow for a thunderstorm to maintain itself for a much longer period of time, strengthen, and become a much more severe thunderstorm that can potentially produce hail, damaging winds, and of course tornadoes.
Late-afternoon supercell over Nebraska
Given this requirement, supercells are most likely to be produced over areas with strong, well-defined air mass boundaries, such as surface fronts or dry lines. As such, the mid-latitudes, which include areas like the Great Plains of North America, are prime locations for such thunderstorms to develop in the spring. This season is when these boundaries begin to develop at greater rates across the continent while the reintroductions of vegetation, along with increased radiative heating, ensure that the environment is much more prime for supercells and the severe weather hazards that come along with them.
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©2019 Meteorologist Gerardo Diaz Jr.
April Showers, Bringing May Flowers? …. Global Precipitation Climatology (Photo Credits: Sharon Sullivan, Global Precipitation Climatology Project)
April showers bring May flowers - or so we’ve been told - this phrase can be traced back to the mid-1500s from a collection of writings known as “A Hundred Good Points of Husbandry” - “Sweet April Showers do spring May Flowers”. But, with portions of the Southwestern U.S. still in moderate to severe drought categories, what does that mean for May flowers?
Precipitation is defined by the AMS Glossary as “liquid or solid phase aqueous particles that originate in the atmosphere and fall to the earth’s surface”. Precipitation is important for understanding climate evolution and hydrological applications ranging from agriculture to flooding. Extensive research has been undertaken in recent decades to develop a global precipitation climatology. The main source of precipitation climatology is from the Global Precipitation Climatology Project (GPCP), a joint effort that attempts to merge data from 6000 rain gauge stations, geostationary and polar-orbiting satellites, radar, and sounding observations in order to estimate total monthly rainfall.
Rain gauge observations have been used to estimate precipitation rate, however, the global distribution of gauges is population dependent and assumes there is no potential losses from the melting of frozen precipitation. Radar can be used to estimate rain rate through comparison of hydrometeor size to the radar reflectivity factor, but beam blocking, attenuation, and great distances from the radar can leave gaps in precipitation climatology. While satellites may tend to underestimate precipitation compared to gauges and radar, they can infer precipitation amounts over oceans, complex terrain, and sparsely populated areas by determining cloud types/depths through the visible and infrared channels.
Annual mean precipitation distributions in mm day-1. The global mean is 2.61 mm day-1, or 37.480 in year-1 (Global Precipitation Climatology Project)
On global, regional, and local scales, precipitation is controlled by the availability of water vapor, temperature, aerosols, cloud type, dynamics (latitude), and orography (local). The Northern Hemisphere tropics precipitate on average 50% more than the Southern, due to a greater proportion of land mass. Precipitation tends to follow a diurnal cycle, but this pattern is regionally dependent. During spring, the best of both precipitation dynamics - winter and summer - converge. The jet stream remains strong, holding onto the cold winter chill, as sunlight warms the lower atmosphere. The Rocky Mountain Range in the central United States typically experiences high-frequency precipitation events in the mid-afternoon summers and early fall (suggesting that high surface temperatures drive convective processes), while early morning rainfall may occur in Thailand and the Bay of Bengal during monsoon season. For New Mexico in particular, the summer monsoon months receive almost half the average precipitation for the year. The poles typically have lower precipitation amounts (<1 mm day-1) due to the lower water vapor content, as colder climates aren’t able to hold as much water vapor in the atmosphere above. Another important phenomena associated with global precipitation variability on interannual time scales is El Niño-Southern Oscillation (ENSO), where changes in sea surface temperature can modify the position of storm tracks in the Northern Hemisphere.
Thus, an accurate precipitation climatology is essential to improve model & satellite verification, make short-term forecasts more effective, and even help to predict shifts in global precipitation patterns in the future. Just as a reminder than even the most unpleasant of things (in this case, the heavy rains of April) can spring forth even the most enjoyable of things - the abundance of May flowers.
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©2019 Meteorologist Sharon Sullivan
Taking A Look Back at Winter 2019 Climate Statistics (Credit: NOAA National Center for Environmental Information-Climate)
Discussion: As the cold days of winter fade away, spring is starting to go into full gear across the United States. The National Center for Environmental Information has released their climate statistics from this past winter. Breaking these statistics down, the overall average temperature for the season (December 2018- February 2019) was 33.4°F. This number is 1.2°F above the average temperature. These averages are based on a record spanning 125 years. This winter ranked the top third warmest of winters since the record began. Regions that experienced these warmer than average winter temperatures included parts of the New England, the Southern Plains, and Southeast Ohio Valley. In Alaska, the average winter temperature was 10.5℉. This was the thirteenth warmest winter for Alaska, 6.9°F warmer than the long-term average. Georgia, Florida, and Tennessee all had overall winter temperatures that ranked in the top ten warmest for their state. Though many areas saw a warmer winter, cooler than average temperatures were present in the Rocky Mountains, the Southwest, and Central and Northern plains. During the end of January, many parts of the Midwest experienced record breaking, downright frigid temperatures. Despite the extreme cold during that time, no state broke a record for cold or warm.
The average total of wintertime precipitation this year was 9.01 inches, which was above average by 2.22 inches. This amount ranks this winter (December 2018-February 2019) as the wettest winter on record, beating the winter of 1997-1998 by just 0.02 inches. Across the contiguous United States, most of the nation experienced above average precipitation rates except for only five states! The standout state was Tennessee, which experienced their wettest winter and February on record, while Wisconsin had their second wettest winter. Snowfall records were broken in Omaha, Nebraska and Nome, Alaska. Omaha had a record breaking 46.1 inches of snowfall which broke their 2003-2004 winter record of 44.3 inches. Nome tallied 69.5 inches of snow with help from a record-breaking February snowfall of 35.6 inches. That record-breaking February snowfall was the highest single February snowfall in Nome since 1920! With all of the snow and rain that fell across the United States this winter, no state ranked below average in the precipitation category.
Winter 2019 was a fairly active season. Across the United States, various weather events occurred. From Washington to Wisconsin, numerous cold temperature and snowfall records were broken in February. In Hawaii, Mauna Kea experienced a temperature of 9 degrees! A storm system known as a Kona Low was the cause bringing snow, heavy winds, and high waves. Across California and the West Coast, an atmospheric river event brought in heavy rainfall. These heavy rains caused flooding on the Russian River, which is located north of Santa Rosa, California. The atmospheric river event also contributed positively to the above average Sierra Nevada Mountains snowpack. In the southeast, heavy rain caused flooding and mudslides, while in the Northeast and Great Lakes, winter storms brought coastal flooding, heavy snowfall, and hurricane force winds.
In other locations across the west, snowfall broke records. In Flagstaff, Arizona, a one-day total of 35.9 inches was recorded! This marks the snowiest day on record for the city. For Las Vegas, Nevada, they saw their first measurable snowfall in over a decade. This winter broke records and brought some of the coldest temperatures that some parts of the country have ever experienced. With the winter cold and snow behind us, springtime temperatures will be right around the corner!
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©2019 Meteorologist Shannon Scully
How Climate Change Might Impact Maple Syrup Production (Credit: Climate Central, NewYorkUpstate.com)
Discussion: Late winter is synonymous with many aspects of the Northeast, such as Winter Storms and lingering cold temperatures. Across the Northeast, late winter is also known for maple syrup production. Sugar maple trees are abundant from the Tennessee Valley into the Northeast, but it is only in the Northeast where the climate is right for tapping the sap from the tree. The combination of the cold nights and warmer days is beneficial for the production of sap from the maple trees. With the difference in temperature between day and night, there is a difference in pressure that allows for the sap to be pushed out of the tree. Sap is then boiled off and turned into maple syrup and other maple products. Scientists are concerned however, that the sugaring season is now being affected by climate change. The maple syrup season usually ranges from February to April but now according to some owners in Upstate NY, those seasons are being cut short with trees not being ready until mid-March.
According to maple tree researchers, the maple season in New England has been starting 8 days earlier and ending 11 days earlier than a half a century ago. In Vermont, researchers are worried due to the fact that Vermont and New York have similar climates. If the temperatures become too warm, it results in less sugar in the sap of the maple trees. The less sugar there is in the sap requires more sap per gallon of maple syrup. Vermont is the biggest producer of maple syrup in the United States. The maple syrup industry is a $141 billion-dollar industry. Maple trees need below freezing temperatures during the winter, and during the early spring need a range of temperatures for the sap to flow. As the winter season continues to change climatologically, it is likely that the Northeast will slowly become the sole hub of Maple Syrup due to the maple trees down south becoming less viable for sap production.
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Photo credit: Climate Central
©2019 Meteorologist Shannon Scully
In the northernmost region of the large island of Hawai’i, there is a tall mountain that separates the east from the west: Kohala Mountain. It has long been a trademark of the region for its incredible effect on the island. It’s responsible for creating the obvious rift in geography between the leeward and windward sides of the mountain that one can see in the image above. What about the mountain though causes one side to be lush with vegetation, while the other is basically a desert?
The answer has to do with orographic uplift, which is the upward movement of air along given mountains. Hawai’i lies within the area covered by the easterly trade winds, causing the eastern side of Kohala Mountain to be the first mountainous region to intercept winds coming over the ocean in northern Hawai’i. That moist air from the Pacific Ocean rises up over the mountains though orographic uplift and then condenses into clouds at the top of the mountain. Consequently, the windward side of Kohala receives plenty of precipitation and moisture, which creates its lush vegetation. However, once the air condenses and precipitates over the east, there is not much moisture left for the west side of the mountain. Instead, dry air falls back down the west side of the mountain and warms up, creating a desert. This is an example of a rain shadow, and they are present all over the world.
One very notable example aside from Hawai’i is the mid-west of the United States. In the continental United States, winds primarily come from the west over the Pacific Ocean. When that air reaches the Rocky Mountains, it creates a rain shadow over the leeward side of the mountains, which is part of the reason why it tends to be so dry in the mid-west. Additionally, the area west of the mountains gets a lot of rain and is why Seattle is known for being so rainy. Other instances of the rain shadow effect creating dry areas include the Atacama Desert in Chile due to the Andes Mountains, and the Gobi Desert in Mongolia due to the Himalayan Mountains.
Since rain shadows heavily impact people and wildlife on both sides of mountain chains, it’s an important phenomenon to know in order to understand the geography and climate of different areas around the world. Although it is only one piece of the puzzle in deciphering why different parts of the planet have different climates, the rain shadow is still an essential element in determining the behavior of the weather throughout the world.
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© 2018 Weather Forecaster Cole Bristow
In recent weeks, the spring-time thaw has been forecasted and broadcasted across the contiguous United States. With this past winter bringing record snowfall to numerous places, the combination of snow melt and spring-time rain will surely create difficult situations for various locations across the U.S. A recent study citing a rise in extreme rain events will also create havoc in an already damp and strenuous environment. The long-time saying of “April showers, bring May flowers” will definitely bloom in popularity with this increase in extreme rain.
Precipitation is an ever changing aspect of an ever changing climate. A one-degree Fahrenheit rise in global temperatures would lead to a four percent increase in water vapor in the atmosphere. This abundance of water vapor would have the potential to strengthen downpours, snow fall and even those “all day” rainfalls. In a recent study NOAA and NCEI indicates that the 10 years with the most extreme one-day precipitation have come all since 1995. The study used conventional climate extremes data that looked at monthly maximum and minimum temperature, daily precipitation and drought data for regions around the globe.
This upward trend of more extreme rain can be seen as a part of other extremes that are on the rise and have been for approximately a decade or so. The NOAA/NCEI Climate Extremes Index evaluates the percentage of the contiguous U.S. that is much above (or below) normal for six indicators that are related to temperature, drought, precipitation and tropical cyclones. This data goes back to 1910, but shows the top four of the five values occurred in 2012, 2015, 2016 and 2017, with 2018 coming in eighth. Of all the climate extremes that this index calculates, water imbalance issues stand out. In the coming decades, water imbalance, which includes precipitation, drought and water scarcity, will have the utmost climate impacts due to the reliance on water as well as the dangers that extreme rainfall and flooding possess.
In recent years, extreme rainfall events have seen a small but steady increase. Along with this, a slight rise in temperature, which is projected, will only increase extreme rainfall events further. To keep up with the NOAA/NCEI Climate Extremes Index, go here.
To learn more about other interesting articles related to global climate issues, be sure to click on the following link: www.globalweatherclimatecenter.com/climate
©2019 Weather Forecaster Alec Kownacki
Spring has Sprung: An Analysis of CPC’s Spring 2019 Outlook (Photo Credits: NOAA’s Climate Prediction Center, Fred Dunn)
NOAA's CPC outlook for April-May-June (updated March 21 2019) ; MLK Memorial in Washington D.C. surrounded by cherry blossoms in March 2018
This morning, the Climate Prediction Center (CPC) released its three-month outlook for spring temperatures and precipitation. An official El Niño declaration was made about a month ago, with positive temperature anomalies reigning in the central Pacific.
The CPC makes 6-10 day outlooks, 8-14 day, monthly, and seasonal outlooks across the United States. For example, the three month spring outlook (April-May-June) gives the probability of of precipitation occurrence on the three upcoming months of the forecast model run. Probability of precipitation will be in one of 3 possible categories: below (B), median (N), or above (A). Categories are defined by separating the 30 years of the most recent climatology period 1981-2010 into the 10 driest years, the middle 10 years, and the wettest 10 years on any given 5-day period. The probability of any category being selected at random is ⅓. The colored shading on the map indicates the degree of confidence. The darker the shading, the greater level of confidence.
For New Mexico, in particular, the Madden-Julian Oscillation, or MJO, played a bigger role in active winter weather systems. But, what does that mean for spring across northern and central New Mexico? Wetter than normal conditions are more likely during El Niño events in the Southwest, especially during the cool season months of winter and spring, in which there is an eastward extension of deep tropical convection. While odds generally favor a wetter winter during El Niño, an analysis of individual stations reveals precipitation to be highly variable from event to event. Temperatures are more of a mixed bag, based on current dynamical and statistical output and historical trends (i.e. whether an earlier spring snowmelt will affect higher elevation temperatures). MJO, on the other hand, is forecast to remain active through the end of the month, where mid-latitudinal teleconnections become weaker during the spring months. While an El Niño event will tilt the odds for a wet winter and spring in New Mexico, it does not guarantee above average precipitation.
Following a round of chilly temperatures and a polar vortex, it looks like the groundhog may have forecasted spring at an opportune time!
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©2019 Meteorologist Sharon Sullivan
Aside from the Thornthwaite Climate Classification system which was reported upon a couple months ago (go here to read that article), the classification system that came before Thornthwaite’s time is the Koppen Climate Classification. The classification was first published by Russian climatologist Vladimir Koppen in 1884. Although it was published in 1884, it wasn’t completed until 1936 after several modifications by Koppen. To add several more modifications, climatologist Rudolf Geiger introduced several other changes that were needed. The two climatologists and their work is what gives this classification system the name of Koppen-Geiger climate classification. But, for the sake of title and to give credit to the creator, it is commonly known as the Koppen climate classification.
Koppen’s aim was to devise formulas that would define climatic boundaries in a way that would correspond to vegetation zones, known as biomes, which were being mapped out during his time. The system divides climates into five main climate groups, with each group being divided based on seasonal precipitation and temperature patterns. These groups are represented by capital letters A, B, C, D and E. All of which, except for B, are defined by temperature criteria. Type B looks more at the amount of precipitation or dryness rather than temperature. The climate designations are as follows: tropical, A; dry/arid, B; temperate, C; continental, D; and polar, E.”
Along with the capital letters to represent the type of climate, Koppen wanted more specific factors to truly identify the climate of a given area. With this in mind, he designated numerous other letters to represent the other features that a climate could have:
As shown in the table above, the lower case letters represent the kind of climate an area possesses. The overall differentiation is based upon temperature with precipitation dividing the classification further. Koppen wanted to show how climates are split up based upon vegetation and the precipitation they receive. He created just that, but with more concentration on temperature and precipitation. This differs from the Thornthwaite Classification System by relying upon the temperature and precipitation of the area. Thornthwaite, who grew up as a farmer and was educated in botany, expanded his system to the characteristics of the area; such as the vegetation type. Thornthwaite measured the precipitation and evaporation of the climate to classify it. To learn more about the Thornthwaite system refer to the link which was provided earlier in this article.
The Koppen classification system was the first of its kind that measured both temperature and precipitation and how they both effect the climate of a given area. Koppen’s system is still heavily used to this day and helps climatologists, along with other scientists, determine how to classify the climate of region.
To learn more about other interesting stories related to global climate issues, be sure to click on the following link: www.globalweatherclimatecenter.com/climate
©2019 Weather Forecaster Alec Kownacki