1.
Satellite imagery
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Satellite imagery consists of images of Earth or other planets collected by satellites. Imaging satellites are operated by governments and businesses around the world, Satellite imaging companies sell images under licence. Images are licensed to governments and businesses such as Apple Maps, the first images from space were taken on sub-orbital flights. The U. S-launched V-2 flight on October 24,1946 took one image every 1.5 seconds. With an apogee of 65 miles, these photos were from five times higher than the previous record, the first satellite photographs of Earth were made on August 14,1959 by the U. S. The first satellite photographs of the Moon might have made on October 6,1959 by the Soviet satellite Luna 3. The Blue Marble photograph was taken from space in 1972, and has very popular in the media. Also in 1972 the United States started the Landsat program, the largest program for acquisition of imagery of Earth from space, Landsat Data Continuity Mission, the most recent Landsat satellite, was launched on 11 February 2013. In 1977, the first real time satellite imagery was acquired by the United Statess KH-11 satellite system, all satellite images produced by NASA are published by NASA Earth Observatory and are freely available to the public. Several other countries have satellite imaging programs, and a collaborative European effort launched the ERS, there are also private companies that provide commercial satellite imagery. Images can be in visible colours and in other spectra, there are also elevation maps, usually made by radar images. Interpretation and analysis of imagery is conducted using specialized remote sensing applications. There are four types of resolution when discussing satellite imagery in remote sensing, spatial, spectral, temporal, and radiometric. GSD is a term containing the optical and systemic noise sources and is useful for comparing how well one sensor can see an object on the ground within a single pixel. For example, the GSD of Landsat is ~30m, which means the smallest unit that maps to a single pixel within an image is ~30m x 30m, the latest commercial satellite has a GSD of 0.41 m. This compares to a 0.3 m resolution obtained by some early military film based Reconnaissance satellite such as Corona, the resolution of satellite images varies depending on the instrument used and the altitude of the satellites orbit. For example, the Landsat archive offers repeated imagery at 30 meter resolution for the planet, Landsat 7 has an average return period of 16 days. For many smaller areas, images with resolution as high as 41 cm can be available, Satellite imagery is sometimes supplemented with aerial photography, which has higher resolution, but is more expensive per square meter
2.
NASA
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President Dwight D. Eisenhower established NASA in 1958 with a distinctly civilian orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29,1958, disestablishing NASAs predecessor, the new agency became operational on October 1,1958. Since that time, most US space exploration efforts have led by NASA, including the Apollo Moon landing missions, the Skylab space station. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle, the agency is also responsible for the Launch Services Program which provides oversight of launch operations and countdown management for unmanned NASA launches. NASA shares data with various national and international such as from the Greenhouse Gases Observing Satellite. Since 2011, NASA has been criticized for low cost efficiency, from 1946, the National Advisory Committee for Aeronautics had been experimenting with rocket planes such as the supersonic Bell X-1. In the early 1950s, there was challenge to launch a satellite for the International Geophysical Year. An effort for this was the American Project Vanguard, after the Soviet launch of the worlds first artificial satellite on October 4,1957, the attention of the United States turned toward its own fledgling space efforts. This led to an agreement that a new federal agency based on NACA was needed to conduct all non-military activity in space. The Advanced Research Projects Agency was created in February 1958 to develop technology for military application. On July 29,1958, Eisenhower signed the National Aeronautics and Space Act, a NASA seal was approved by President Eisenhower in 1959. Elements of the Army Ballistic Missile Agency and the United States Naval Research Laboratory were incorporated into NASA, earlier research efforts within the US Air Force and many of ARPAs early space programs were also transferred to NASA. In December 1958, NASA gained control of the Jet Propulsion Laboratory, NASA has conducted many manned and unmanned spaceflight programs throughout its history. Some missions include both manned and unmanned aspects, such as the Galileo probe, which was deployed by astronauts in Earth orbit before being sent unmanned to Jupiter, the experimental rocket-powered aircraft programs started by NACA were extended by NASA as support for manned spaceflight. This was followed by a space capsule program, and in turn by a two-man capsule program. This goal was met in 1969 by the Apollo program, however, reduction of the perceived threat and changing political priorities almost immediately caused the termination of most of these plans. NASA turned its attention to an Apollo-derived temporary space laboratory, to date, NASA has launched a total of 166 manned space missions on rockets, and thirteen X-15 rocket flights above the USAF definition of spaceflight altitude,260,000 feet. The X-15 was an NACA experimental rocket-powered hypersonic research aircraft, developed in conjunction with the US Air Force, the design featured a slender fuselage with fairings along the side containing fuel and early computerized control systems
3.
Moderate-resolution imaging spectroradiometer
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The instruments capture data in 36 spectral bands ranging in wavelength from 0.4 µm to 14.4 µm and at varying spatial resolutions. Together the instruments image the entire Earth every 1 to 2 days, MODIS has used the marine optical buoy for vicarious calibration. MODIS is succeeded by the VIIRS instrument on board the Suomi NPP satellite launched in 2011, the MODIS characterization support team is dedicated to the production of high-quality MODIS calibrated product which is a precursor to every geophysical science product. A detailed description of the MCST mission statement and other details can be found at MCST Web, with its low spatial resolution but high temporal resolution, MODIS data is useful to track changes in the landscape over time. The United States Forest Services Remote Sensing Applications Center analyzes MODIS imagery on a basis to provide information for the management. The following MODIS Level 3 datasets are available from NASA, as processed by the Collection 5 software, most of the data is available in the HDF-EOS format — a variant of Hierarchical Data Format prescribed for the data derived from Earth Observing System missions. Imaging spectroscopy NASA World Wind Official NASA site MODIS bands and spectral ranges MODIS Images of the Day MODIS Image of the Day – Google Gadget referring to MODIS image of the day
4.
Sky
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The sky is everything that lies above the surface of the Earth, including the atmosphere and outer space. In the field of astronomy, the sky is called the celestial sphere. This is viewed from Earths surface as a dome where the Sun, stars, planets. The celestial sphere is divided into regions called constellations. Usually, the sky is used informally as the point of view from the Earths surface, however. In some cases, such as in discussing the weather, the sky refers to only the lower, during daylight, the sky appears to be blue because air scatters blue sunlight more than it scatters red. At night, the sky appears to be a dark surface or region scattered with stars. During the day, the Sun can be seen in the sky obscured by clouds. In the night sky the Moon, planets and stars are visible in the sky, some of the natural phenomena seen in the sky are clouds, rainbows, and aurorae. Lightning and precipitation can also be seen in the sky during storms, birds, insects, aircraft, and kites are often considered to fly in the sky. Due to human activities, smog during the day and light pollution during the night are often seen above large cities. Except for light that directly from the sun, most of the light in the day sky is caused by scattering. The scattering due to molecule sized particles is greater in the forward and backward directions than it is in the lateral direction. Scattering is significant for light at all visible wavelengths but is stronger at the end of the visible spectrum, meaning that the scattered light is bluer than its source. The remaining sunlight, having lost some of its wavelength components. Scattering also occurs more strongly in clouds. Individual water droplets exposed to light will create a set of colored rings. If a cloud is thick enough, scattering from water droplets will wash out the set of colored rings
5.
Okta
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In meteorology, an okta is a unit of measurement used to describe the amount of cloud cover at any given location such as a weather station. Sky conditions are estimated in terms of how many eighths of the sky are covered in cloud, in addition, in the SYNOP code there is an extra cloud cover indicator 9 indicating that the sky is totally obscured, usually due to dense fog or heavy snow. Although relatively straightforward to measure, oktas only estimate cloud cover in terms of the area of the sky covered by clouds and they do not account for cloud type or thickness, and this limits their use for estimating cloud albedo or surface solar radiation receipt. Cloud oktas can also be measured using satellite imagery from geostationary satellites equipped with high-resolution image sensors such as Himawari-8, similar to traditional approaches, satellite images do not account for cloud composition
6.
Sunshine duration
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It is a general indicator of cloudiness of a location, and thus differs from insolation, which measures the total energy delivered by sunlight over a given period. Sunshine duration is usually expressed in hours per year, or in hours per day, the first measure indicates the general sunniness of a location compared with other places, while the latter allows for comparison of sunshine in various seasons in the same location. Another often-used measure is percentage ratio of recorded bright sunshine duration, an important use of sunshine duration data is to characterize the climate of sites, especially of health resorts. This also takes account the psychological effect of strong solar light on human well-being. It is often used to promote tourist destinations, if the Sun were to be above the horizon 50% of the time for a standard year consisting of 8,760 hours, apparent maximal daytime duration would be 4,380 hours for any point on Earth. However, there are physical and astronomical effects that change that picture, namely, atmospheric refraction allows the Sun to be still visible even when it physically sets below the horizon. For that reason, average daytime is longest in polar areas, places on the Arctic Circle have the longest total annual daytime,4,647 hours, while the North Pole receives 4,575. Because of elliptic nature of the Earths orbit, the Southern Hemisphere is not symmetrical, the Equator has a total daytime of 4,422 hours per year. Given the theoretical maximum of daytime duration for a given location, bright sunshine hours represent the total hours when the sunlight is stronger than a specified threshold, as opposed to just visible hours. Visible sunshine, for example, occurs around sunrise and sunset, measurement is performed by instruments called sunshine recorders. For the specific purpose of sunshine duration recording, Campbell–Stokes recorders are used, when the intensity exceeds a pre-determined threshold, the tape burns. The total length of the trace is proportional to the number of bright hours. Another type of recorder is the Jordan sunshine recorder, newer, electronic recorders have more stable sensitivity than that of the paper tape. In 2003, the duration was finally defined as the period during which direct solar irradiance exceeds a threshold value of 120 W/m². The sky is clear in these regions, and fair weather is virtually perpetual, the descending branch of the Hadley cell and the long-term lack of atmospheric disturbances helps to explain the seemingly endless supply of sunny, cloud-free days in the deserts. Low clouding conditions are associated with rainfall shortage, as seen in these dry regions. In the belt encompassing northern Chad and the Tibesti Mountains, northern Sudan, southern Libya, some places in the interior of the Arabian Peninsula receive 3, 600–3,800 hours of bright sunshine annually. The largest sun-baked region in the world is North Africa, the sunniest month in the world is December in Eastern Antarctica, with almost 23 hours of bright sun daily
7.
Cirrus cloud
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Cirrus is a genus of atmospheric cloud generally characterized by thin, wispy strands, giving the type its name from the Latin word cirrus, meaning a ringlet or curling lock of hair. This cloud can form anywhere between 16,500 and 45,000 feet in the sky, the strands of cloud sometimes appear in tufts of a distinctive form referred to by the common name of mares tails. On planet Earth, cirrus generally appears white or light gray in color and it forms when water vapor undergoes deposition at altitudes above 5,500 m in temperate regions and above 6,400 m in tropical regions. It also forms from the outflow of tropical cyclones or the anvils of cumulonimbus cloud, since cirrus clouds arrive in advance of the frontal system or tropical cyclone, it indicates that weather conditions may soon deteriorate. While it indicates the arrival of precipitation, cirrus clouds only produce fall streaks, jet stream-powered cirrus can grow long enough to stretch across continents while remaining only a few kilometers deep. When visible light interacts with the ice crystals in cirrus cloud, it produces optical phenomena such as sun dogs, Cirrus is known to raise the temperature of the air beneath the main cloud layer by an average of 10 °C. When the individual filaments become so extensive that they are virtually indistinguishable from one another, convection at high altitudes can produce another high-based genus called cirrocumulus, a pattern of small cloud tufts that contain droplets of supercooled water. Cirrus clouds form on planets, including Mars, Jupiter, Saturn, Uranus. They have even seen on Titan, one of Saturns moons. Some of these extraterrestrial cirrus clouds are composed of ammonia or methane ice rather than water ice, the term cirrus is also used for certain interstellar clouds composed of sub-micrometer-sized dust grains. Cirrus cloud ranges in thickness from 100 m to 8,000 m, with an average thickness of 1,500 m. There are, on average,30 ice crystals per liter, but this ranges from one ice crystal per 10,000 liters to 10,000 ice crystals per liter, a difference of eight orders of magnitude. The length of each of these ice crystals is usually 0.25 millimeters long, the ice crystals in contrails are much smaller than those in naturally occurring cirrus cloud, as they are around 0.001 millimeters to 0.1 millimeters in length. Cirrus can vary in temperature from −20 °C to −30 °C, the ice crystals in cirrus clouds have different shapes in addition to different sizes. Some shapes include solid columns, hollow columns, plates, rosettes, the shape of the ice crystals is determined by the air temperature, atmospheric pressure, and ice supersaturation. Cirrus in temperate regions typically have the shapes segregated by type, in the northern Arctic region, cirrus tend to be composed of only the columns, plates, and conglomerations, and these crystals tend to be at least four times larger than the minimum size. In Antarctica, cirrus are usually composed of only the columns, scientists have studied the characteristics of cirrus using several different methods. One, Light Detection and Ranging, gives highly accurate information on the altitude, length
8.
Climate
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Climate is the statistics of weather, usually over a 30-year interval. Climate differs from weather, in that weather only describes the conditions of these variables in a given region. A regions climate is generated by the system, which has five components, atmosphere, hydrosphere, cryosphere, lithosphere. The climate of a location is affected by its latitude, terrain, climates can be classified according to the average and the typical ranges of different variables, most commonly temperature and precipitation. The most commonly used classification scheme was the Köppen climate classification, the Bergeron and Spatial Synoptic Classification systems focus on the origin of air masses that define the climate of a region. Paleoclimatology is the study of ancient climates, Climate models are mathematical models of past, present and future climates. Climate change may occur long and short timescales from a variety of factors. For example, a 3°C change in mean annual temperature corresponds to a shift in isotherms of approximately 300–400 km in latitude or 500 m in elevation, therefore, species are expected to move upwards in elevation or towards the poles in latitude in response to shifting climate zones. Climate is commonly defined as the weather averaged over a long period, the standard averaging period is 30 years, but other periods may be used depending on the purpose. Climate also includes statistics other than the average, such as the magnitudes of day-to-day or year-to-year variations, the classical period is 30 years, as defined by the World Meteorological Organization. These quantities are most often surface variables such as temperature, precipitation, Climate in a wider sense is the state, including a statistical description, of the climate system. The World Meteorological Organization describes climate normals as reference points used by climatologists to compare current climatological trends to that of the past or what is considered normal, a Normal is defined as the arithmetic average of a climate element over a 30-year period. A30 year period is used, as it is enough to filter out any interannual variation or anomalies. The WMO originated from the International Meteorological Organization which set up a commission for climatology in 1929. At its 1934 Wiesbaden meeting the commission designated the thirty-year period from 1901 to 1930 as the reference time frame for climatological standard normals. In 1982 the WMO agreed to update climate normals, and in these were completed on the basis of climate data from 1 January 1961 to 31 December 1990. The difference between climate and weather is usefully summarized by the popular phrase Climate is what you expect, weather is what you get. Over historical time spans there are a number of nearly constant variables that determine climate, including latitude, altitude, proportion of land to water and these change only over periods of millions of years due to processes such as plate tectonics
