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Thaw (weather)
Thaw is the period when the snow and ice melt, at the end of the winter, in cold climates. January thaw January thaw is a term applied to a thaw or rise in temperature in mid-winter found in mid-latitude North America. Sinusoidal estimates of expected temperatures, for northern locales, usually place the lowest temperatures around January 23 and the highest around July 24, and provide fairly accurate estimates of temperature expectations. Actual average temperatures in North America usually significantly differ twice over the course of the year * Mid-autumn temperatures tend to be warmer than predicted by the sinusoidal model, creating the impression of extended summer warmth known as Indian summer. * For five days around January 25, temperatures are usually significantly warmer than predicted by the sinusoidal estimate, and also warmer than neighboring temperatures on both sides. During this "thaw" period, usually lasting for about a week, temperatures are generally a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sinusoidal Model
In statistics, signal processing, and time series analysis, a sinusoidal model is used to approximate a sequence ''Yi'' to a sine function: :Y_i = C + \alpha\sin(\omega T_i + \phi) + E_i where ''C'' is constant defining a mean level, α is an amplitude for the sine, ω is the angular frequency, ''Ti'' is a time variable, φ is the phase-shift, and ''Ei'' is the error sequence. This sinusoidal model can be fit using nonlinear least squares; to obtain a good fit, routines may require good starting values for the unknown parameters. Fitting a model with a single sinusoid is a special case of spectral density estimation and least-squares spectral analysis. Good starting values Good starting value for the mean A good starting value for ''C'' can be obtained by calculating the mean of the data. If the data show a trend estimation, trend, i.e., the assumption of constant location is violated, one can replace ''C'' with a linear or quadratic least squares fit. That is, the model b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weather Lore
Weather lore is the body of informal folklore related to the prediction of the weather and its greater meaning. Much like regular folklore, weather lore is passed down through speech and writing from normal people without the use of external measuring instruments. The origin of weather lore can be dated back to primeval men and their usage of star studying in navigation. However, more recently during the Late Middle Ages, the works of two Greek philosopher-poets, Theophrastus of Eresus on Lesbos and Aratus of Macedonia, are known for shaping the prediction of weather. Theophrastus and Aratus collated their works in two main collections for weather lore: ''On Weather Signs'' and ''On Winds.'' These were used for helping farmers with harvest, merchants for trade and determining the weather the next day. Astrology and weather lore have been closely interlinked for many years - with each planet often being associated with a weather state. For example, Mars is red and must therefore ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chinook Wind
Chinook winds, or simply Chinooks, are two types of prevailing warm, generally westerly winds in western North America: Coastal Chinooks and interior Chinooks. The coastal Chinooks are persistent seasonal, wet, southwesterly winds blowing in from the ocean. The interior Chinooks are occasional warm, dry föhn winds blowing down the eastern sides of interior mountain ranges. The coastal Chinooks were the original term, used along the northwest coast, and the term in the interior of North America is later and derives from the coastal term. * Along the Pacific Northwest coast, where the name is pronounced ('chin'+'uk'), the name refers to wet, warm winds off the ocean from the southwest; this is the original use of the term. The coastal Chinook winds deliver tremendous amounts of moisture both as rain along the coast and snow in the coastal mountains, that sustain the characteristic temperate rainforests and climate of the Pacific Northwest. * In North American western interior, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edward George Bowen
Edward George "Taffy" Bowen, CBE, FRS (14 January 1911 – 12 August 1991) was a Welsh physicist who made a major contribution to the development of radar. He was also an early radio astronomer, playing a key role in the establishment of radioastronomy in Australia and the United States. Early years Edward George Bowen was born at Cockett in Swansea, south Wales, to George Bowen and Ellen Ann (née Owen). George Bowen was a steelworker in a Swansea tinplate works. From an early age Bowen developed a strong interest in radio and cricket. He entered Swansea University and read physics and related subjects. He graduated with a First-Class Honours degree in 1930, and continued with postgraduate research on X-rays and the structure of alloys, earning an MSc in 1931. He completed his doctorate under Professor E.V. Appleton at King's College London. As part of his research, Bowen spent a large part of 1933 and 1934 working with a cathode-ray direction finder at the Radio Research S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Singularity (climate)
A singularity is a weather phenomenon likely to occur with reasonable regularity around a specific approximate calendar date, Barry R.G. & Chorley R.J. (1987), ''Atmosphere, Weather & Climate'', 5th ed, Routledge, outside of more general seasonal weather patterns (e.g., that May Day is usually warmer than New Year's Day in northern locales). The existence of singularities is disputed, some considering them due to seeing patterns in noise and statistical artifacts from small samples. In North America, the most significant purported singularities are January thaw (warmer weather around January 25) and Indian summer (warmer weather in mid-autumn). More fanciful ones include the British tradition that rain on St. Swithun's Day (15 July) will be followed by forty days and nights of rain, and similar folk beliefs around groundhog day. Studies Although folk tales such as St Swithun's Day generally have little credibility, some of these events have a more solid basis. Early scientific ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canada
Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by total area. Its southern and western border with the United States, stretching , is the world's longest binational land border. Canada's capital is Ottawa, and its three largest metropolitan areas are Toronto, Montreal, and Vancouver. Indigenous peoples have continuously inhabited what is now Canada for thousands of years. Beginning in the 16th century, British and French expeditions explored and later settled along the Atlantic coast. As a consequence of various armed conflicts, France ceded nearly all of its colonies in North America in 1763. In 1867, with the union of three British North American colonies through Confederation, Canada was formed as a federal dominion of four provinces. This began an accretion of provinces an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indian Summer
An Indian summer is a period of unseasonably warm, dry weather that sometimes occurs in autumn in temperate regions of the northern hemisphere. Several sources describe a true Indian summer as not occurring until after the first frost, or more specifically the first "killing" frost. Etymology The late 19th-century lexicographer Albert Matthews made an exhaustive search of early American literature in an attempt to discover who coined the expression. The earliest reference he found dated to 1851. He also found the phrase in a letter written in England in 1778, but discounted that as a coincidental use of the phrase. Later research showed that the earliest known reference to Indian summer in its current sense occurs in an essay written in the United States circa 1778 by J. Hector St. John de Crevecoeur. The letter was first published in French. The essay remained unavailable in the United States until the 1920s. Although the exact origins of the term are uncertain, it was perhaps ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mean
There are several kinds of mean in mathematics, especially in statistics. Each mean serves to summarize a given group of data, often to better understand the overall value (magnitude and sign) of a given data set. For a data set, the ''arithmetic mean'', also known as "arithmetic average", is a measure of central tendency of a finite set of numbers: specifically, the sum of the values divided by the number of values. The arithmetic mean of a set of numbers ''x''1, ''x''2, ..., x''n'' is typically denoted using an overhead bar, \bar. If the data set were based on a series of observations obtained by sampling from a statistical population, the arithmetic mean is the ''sample mean'' (\bar) to distinguish it from the mean, or expected value, of the underlying distribution, the ''population mean'' (denoted \mu or \mu_x).Underhill, L.G.; Bradfield d. (1998) ''Introstat'', Juta and Company Ltd.p. 181/ref> Outside probability and statistics, a wide range of other notions of mean are o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snow
Snow comprises individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo further changes. It consists of frozen crystalline water throughout its life cycle, starting when, under suitable conditions, the ice crystals form in the atmosphere, increase to millimeter size, precipitate and accumulate on surfaces, then metamorphose in place, and ultimately melt, slide or sublimate away. Snowstorms organize and develop by feeding on sources of atmospheric moisture and cold air. Snowflakes nucleate around particles in the atmosphere by attracting supercooled water droplets, which freeze in hexagonal-shaped crystals. Snowflakes take on a variety of shapes, basic among these are platelets, needles, columns and rime. As snow accumulates into a snowpack, it may blow into drifts. Over time, accumulated snow metamorphoses, by sintering, sublimation and freeze-thaw. Where the climate is co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sine Wave
A sine wave, sinusoidal wave, or just sinusoid is a curve, mathematical curve defined in terms of the ''sine'' trigonometric function, of which it is the graph of a function, graph. It is a type of continuous wave and also a Smoothness, smooth periodic function. It occurs often in mathematics, as well as in physics, engineering, signal processing and many other fields. Formulation Its most basic form as a function of time (''t'') is: y(t) = A\sin(2 \pi f t + \varphi) = A\sin(\omega t + \varphi) where: * ''A'', ''amplitude'', the peak deviation of the function from zero. * ''f'', ''frequency, ordinary frequency'', the ''Real number, number'' of oscillations (cycles) that occur each second of time. * ''ω'' = 2''f'', ''angular frequency'', the rate of change of the function argument in units of radians per second. * \varphi, ''phase (waves), phase'', specifies (in radians) where in its cycle the oscillation is at ''t'' = 0. When \varphi is non-zero, the entire waveform appears to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
North America
North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Caribbean Sea, and to the west and south by the Pacific Ocean. Because it is on the North American Plate, North American Tectonic Plate, Greenland is included as a part of North America geographically. North America covers an area of about , about 16.5% of Earth's land area and about 4.8% of its total surface. North America is the third-largest continent by area, following Asia and Africa, and the list of continents and continental subregions by population, fourth by population after Asia, Africa, and Europe. In 2013, its population was estimated at nearly 579 million people in List of sovereign states and dependent territories in North America, 23 independent states, or about 7.5% of the world's population. In Americas (terminology)#Human ge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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