Climate is the long-term weather pattern in a region, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorological variables that are commonly measured are temperature, humidity, atmospheric pressure, wind, and precipitation. In a broader sense, climate is the state of the components of the climate system, including the atmosphere, hydrosphere, cryosphere, lithosphere and biosphere and the interactions between them. The climate of a location is affected by its latitude, longitude, terrain, altitude, land use and nearby water bodies and their currents.
Climatology or climate science is the scientific study of Earth's climate, typically defined as weather conditions averaged over a period of at least 30 years. Climate concerns the atmospheric condition during an extended to indefinite period of time; weather is the condition of the atmosphere during a relative brief period of time. The main topics of research are the study of climate variability, mechanisms of climate changes and modern climate change. This topic of study is regarded as part of the atmospheric sciences and a subdivision of physical geography, which is one of the Earth sciences. Climatology includes some aspects of oceanography and biogeochemistry.
The instrumental temperature record is a record of temperatures within Earth's climate based on direct, instrument-based measurements of air temperature and ocean temperature. Instrumental temperature records are distinguished from indirect reconstructions using climate proxy data such as from tree rings and ocean sediments. Instrument-based data are collected from thousands of meteorological stations, buoys and ships around the globe. Whilst many heavily-populated areas have a high density of measurements, observations are more widely spread in sparsely populated areas such as polar regions and deserts, as well as over many parts of Africa and South America. Measurements were historically made using mercury or alcohol thermometers which were read manually, but are increasingly made using electronic sensors which transmit data automatically. The longest-running temperature record is the Central England temperature data series, which starts in 1659. The longest-running quasi-global records start in 1850.
The Palmer drought index, sometimes called the Palmer drought severity index (PDSI), is a regional drought index commonly used for monitoring drought events and studying areal extent and severity of drought episodes. The index uses precipitation and temperature data to study moisture supply and demand using a simple water balance model. It was developed by meteorologist Wayne Palmer, who first published his method in the 1965 paper Meteorological Drought for the Office of Climatology of the U.S. Weather Bureau.
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls from clouds due to gravitational pull. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. Precipitation occurs when a portion of the atmosphere becomes saturated with water vapor, so that the water condenses and "precipitates" or falls. Thus, fog and mist are not precipitation but colloids, because the water vapor does not condense sufficiently to precipitate. Two processes, possibly acting together, can lead to air becoming saturated: cooling the air or adding water vapor to the air. Precipitation forms as smaller droplets coalesce via collision with other rain drops or ice crystals within a cloud. Short, intense periods of rain in scattered locations are called showers.
The Climatic Research Unit (CRU) is a component of the University of East Anglia and is one of the leading institutions concerned with the study of natural and anthropogenic climate change.
London features a temperate oceanic climate (Cfb). This gives the city cool winters, warm summers with precipitation fairly evenly distributed all year round. London has a very rich history of meteorological observations, with precipitation records beginning as early as January 1697 at Kew Gardens. Irregular observations were made at multiple locations in the ensuing years. An observing station has been located at Greenwich since 1841, giving London its longest continuous reliable temperature series. Other stations include Heathrow, beginning in 1948, Hampstead, beginning in 1910, Northolt, beginning in 1948, and St James's Park, beginning in 1910.
The Winkler Index, sometimes known as the Winkler Scale or WinklerRegions, is a technique for classifying the climate of wine growing regions based on heat summation or growing degree-days. In the system, geographical areas are divided into five climate regions based on temperature converted to growing degree-days, and is commonly known as Regions I–V. The system was developed at the University of California, Davis by A. J. Winkler and Maynard Amerine.
The Global Historical Climatology Network (GHCN) is a data set of temperature, precipitation and pressure records managed by the National Climatic Data Center (NDCC), Arizona State University and the Carbon Dioxide Information Analysis Center.
Over the last two centuries many environmental chemical observations have been made from a variety of ground-based, airborne, and orbital platforms and deposited in databases. Many of these databases are publicly available. All of the instruments mentioned in this article give online public access to their data. These observations are critical in developing our understanding of the Earth's atmosphere and issues such as climate change, ozone depletion and air quality. Some of the external links provide repositories of many of these datasets in one place. For example, the Cambridge Atmospheric Chemical Database, is a large database in a uniform ASCII format. Each observation is augmented with the meteorological conditions such as the temperature, potential temperature, geopotential height, and equivalent PV latitude.
The climate of the Arctic is characterized by long, cold winters and short, cool summers. There is a large amount of variability in climate across the Arctic, but all regions experience extremes of solar radiation in both summer and winter. Some parts of the Arctic are covered by ice year-round, and nearly all parts of the Arctic experience long periods with some form of ice on the surface.
Surface weather observations are the fundamental data used for safety as well as climatological reasons to forecast weather and issue warnings worldwide. They can be taken manually, by a weather observer, by computer through the use of automated weather stations, or in a hybrid scheme using weather observers to augment the otherwise automated weather station. The ICAO defines the International Standard Atmosphere (ISA), which is the model of the standard variation of pressure, temperature, density, and viscosity with altitude in the Earth's atmosphere, and is used to reduce a station pressure to sea level pressure. Airport observations can be transmitted worldwide through the use of the METAR observing code. Personal weather stations taking automated observations can transmit their data to the United States mesonet through the Citizen Weather Observer Program (CWOP), the UK Met Office through their Weather Observations Website (WOW), or internationally through the Weather Underground Internet site. A thirty-year average of a location's weather observations is traditionally used to determine the station's climate. In the US a network of Cooperative Observers make a daily record of summary weather and sometimes water level information.
The climate of Ireland is mild, humid and changeable with abundant rainfall and a lack of temperature extremes. Ireland's climate is defined as a temperate oceanic climate, or Cfb on the Köppen climate classification system, a classification it shares with most of northwest Europe. The island receives generally warm summers and cool winters.
CLIMAT is a code for reporting monthly climatological data assembled at land-based meteorological surface observation sites to data centres. CLIMAT-coded messages contain information on several meteorological variables that are important to monitor characteristics, changes, and variability of climate. Usually these messages are sent and exchanged via the Global Telecommunication System (GTS) of the World Meteorological Organisation (WMO). Modifications of the CLIMAT code are the CLIMAT SHIP and CLIMAT TEMP / CLIMAT TEMP SHIP codes which serve to report monthly climatological data assembled at ocean-based meteorological surface observation sites and at land-/ocean-based meteorological upper-air observation sites, respectively. The monthly values included usually are obtained by averaging observational values of one or several daily observations over the respective month.
ʽAziziya, sometimes spelled El Azizia, is a small town and it was the capital of the Jafara district in northwestern Libya, 41 kilometres (25 mi) southwest of the capital Tripoli. From 1918 to 1922 it was the capital of the Tripolitanian Republic, the first formal republic in the Arab world. Before 2001 it was in the ʽAziziya District and its capital. ʽAziziya is a major trade centre of the Sahel Jeffare plateau, being on a trade route from the coast to the Nafusa Mountains and the Fezzan region to the south. As of 2006, the town's population has been estimated at over 23,399.
An atmospheric reanalysis is a meteorological and climate data assimilation project which aims to assimilate historical atmospheric observational data spanning an extended period, using a single consistent assimilation scheme throughout.
Homogenization in climate research means the removal of non-climatic changes. Next to changes in the climate itself, raw climate records also contain non-climatic jumps and changes, for example due to relocations or changes in instrumentation. The most used principle to remove these inhomogeneities is the relative homogenization approach in which a candidate station is compared to a reference time series based on one or more neighboring stations. The candidate and reference station(s) experience about the same climate, non-climatic changes that happen only in one station can thus be identified and removed.
The National Centers for Environmental Information (NCEI), an agency of the United States government, manages one of the world's largest archives of atmospheric, coastal, geophysical, and oceanic data, containing information that ranges from the surface of the sun to Earth's core, and from ancient tree ring and ice core records to near-real-time satellite images.
Ingeborg Auer is an Austrian climatologist, known for her work on Project HISTALP.
Lisa Victoria Alexander is an international expert on heatwaves. She received the Dorothy Hill Medal for her research on climate extremes, the frequency and intensity of heatwaves, and has provided evidence that the frequency and intensity of heatwaves will be influenced by the quantity of anthropogenic greenhouse gas emissions, in particular carbon dioxide. She was a contributing author to the Intergovernmental Panel on Climate Change (IPCC) reports, including the fifth assessment report.
