A season is a division of the year marked by changes in weather and hours of daylight. Seasons result from the orbit of the Earth around the Sun. During May and July, the northern hemisphere is exposed to direct sunlight because the hemisphere faces the sun. The same is true of the hemisphere in November, December. It is the tilt of the Earth that causes the Sun to be higher in the sky during the months which increases the solar flux. However, due to lag, June and August are the hottest months in the northern hemisphere and December, January. In temperate and subpolar regions, four calendar-based seasons are recognized, summer, autumn or fall. Ecologists often use a model for temperate climate regions, vernal, serotinal, autumnal. Many tropical regions have two seasons, the rainy, wet, or monsoon season and the dry season, some have a third cool, mild, or harmattan season. Seasons often held special significance for agrarian societies, whose lives revolved around planting and harvest times, in some parts of the world, some other seasons capture the timing of important ecological events such as hurricane season, tornado season, and wildfire season.
The most historically important of these are the three seasons—flood and low water—which were previously defined by the annual flooding of the Nile in Egypt. The seasons result from the Earths axis of rotation being tilted with respect to its orbital plane by an angle of approximately 23.5 degrees, regardless of the time of year, the northern and southern hemispheres always experience opposite seasons. This is because during summer or winter, one part of the planet is directly exposed to the rays of the Sun than the other. For approximately half of the year, the northern hemisphere tips toward the Sun, for the other half of the year, the same happens, but in the southern hemisphere instead of the northern, with the maximum around December 21. The two instants when the Sun is directly overhead at the Equator are the equinoxes. Also at that moment, both the North Pole and the South Pole of the Earth are just on the terminator, and hence day and night are equally divided between the northern and southern hemispheres.
Around the March equinox, the northern hemisphere will be experiencing spring as the hours of daylight increase, the effect of axial tilt is observable as the change in day length and altitude of the Sun at noon during a year. Between this effect and the daylight hours, the axial tilt of the Earth accounts for most of the seasonal variation in climate in both hemispheres
Pitch is a name for any of a number of viscoelastic polymers. Pitch can be natural or manufactured, derived from petroleum, coal tar or plants, various forms of pitch may be called tar, bitumen or asphalt. Pitch produced from plants is known as resin. Some products made from plant resin are known as rosin, Pitch was traditionally used to help caulk the seams of wooden sailing vessels. Pitch may be used to waterproof wooden containers and in the making of torches, petroleum-derived pitch is black in colour, hence the adjectival phrase, pitch-black. Naturally occurring asphalt/bitumen, a type of pitch, is a viscoelastic polymer and this means that even though it seems to be solid at room temperature and can be shattered with a hard impact, it is actually fluid and will flow over time, but extremely slowly. The pitch drop experiment taking place at University of Queensland is an experiment which demonstrates the flow of a piece of pitch over many years. For the experiment, pitch was put in a glass funnel, since the pitch was allowed to start dripping in 1930, only nine drops have fallen.
It was calculated in the 1980s that the pitch in the experiment has a viscosity approximately 230 billion times that of water, the eighth drop fell on 28 November 2000, and the ninth drop fell on 17 April 2014. Another experiment was begun by a colleague of Nobel Prize winner Ernest Walton in the department of Trinity College in Ireland in 1944. Over the years, the pitch had produced several drops, on Thursday, July 11,2013 scientists at Trinity College caught pitch dripping from a funnel on camera for the first time. The viscoelastic properties of pitch make it the vehicle of choice for polishing high-quality optical lenses, in use the pitch is formed into a lap or polishing surface, which is charged with iron oxide or cerium oxide. The surface to be polished is pressed into the pitch, rubbed against the surface so formed, the ability of pitch to flow, albeit slowly, keeps it in constant uniform contact with the optical surface. The heating of wood tar and pitch to drip away from the wood.
Birchbark is used to make birch-tar, a particularly fine tar, the terms tar and pitch are often used interchangeably. However, pitch is considered solid, while tar is more liquid. Traditionally, pitch that was used for waterproofing buckets, barrels and it is used to make Cutlers resin. Asphaltene Tar The Pitch Drop Experiment Pine Tar Production Primitive tar and charcoal production
A mineral is a naturally occurring chemical compound, usually of crystalline form and abiogenic in origin. A mineral has one specific chemical composition, whereas a rock can be an aggregate of different minerals or mineraloids, the study of minerals is called mineralogy. There are over 5,300 known mineral species, over 5,070 of these have been approved by the International Mineralogical Association, the silicate minerals compose over 90% of the Earths crust. The diversity and abundance of species is controlled by the Earths chemistry. Silicon and oxygen constitute approximately 75% of the Earths crust, which translates directly into the predominance of silicate minerals, minerals are distinguished by various chemical and physical properties. Differences in chemical composition and crystal structure distinguish the various species, changes in the temperature, pressure, or bulk composition of a rock mass cause changes in its minerals. Minerals can be described by their various properties, which are related to their chemical structure.
Common distinguishing characteristics include crystal structure and habit, lustre, colour, tenacity, fracture, more specific tests for describing minerals include magnetism, taste or smell and reaction to acid. Minerals are classified by key chemical constituents, the two dominant systems are the Dana classification and the Strunz classification, the silicate class of minerals is subdivided into six subclasses by the degree of polymerization in the chemical structure. All silicate minerals have a unit of a 4− silica tetrahedron—that is, a silicon cation coordinated by four oxygen anions. These tetrahedra can be polymerized to give the subclasses, disilicates, inosilicates, other important mineral groups include the native elements, oxides, carbonates and phosphates. The first criterion means that a mineral has to form by a natural process, stability at room temperature, in the simplest sense, is synonymous to the mineral being solid. More specifically, a compound has to be stable or metastable at 25 °C, modern advances have included extensive study of liquid crystals, which extensively involve mineralogy.
Minerals are chemical compounds, and as such they can be described by fixed or a variable formula, many mineral groups and species are composed of a solid solution, pure substances are not usually found because of contamination or chemical substitution. Finally, the requirement of an ordered atomic arrangement is usually synonymous with crystallinity, crystals are periodic, an ordered atomic arrangement gives rise to a variety of macroscopic physical properties, such as crystal form and cleavage. There have been recent proposals to amend the definition to consider biogenic or amorphous substances as minerals. The formal definition of an approved by the IMA in 1995, A mineral is an element or chemical compound that is normally crystalline. However, if geological processes were involved in the genesis of the compound, Mineral classification schemes and their definitions are evolving to match recent advances in mineral science
A seep is a moist or wet place where water, usually groundwater, reaches the earths surface from an underground aquifer. Seeps are usually not of sufficient volume to be flowing beyond their above-ground location and they are part of the limnology-geomorphology system. Like a higher volume spring, the water is only from underground sources, seeps mostly occur in lower elevation areas because water runs downhill, but can happen higher up if the groundwater present is abundant enough. Along with natural seeps, man made seeps can occur by digging anywhere where there is wet ground and this method can be useful for survival purposes and helps the local wildlife by adding another water source to the area. Seeps often form a puddle, and are important for wildlife, bird. When they support mud-puddling many butterfly species can obtain nutrients such as salts and amino acids, seep is often used in environmental sciences to define an exfiltration zone where contaminated water, e. g. from waste dumps, leaves a waste system area.
Seeps are often important smaller wildlife water sources, and indicated by lower riparian vegetation, seeps can contribute to streams. If a stream is flowing below a water table the stream receives contributions from the water via seepage. This allows for a drainage of the water along with creating a more substantial stream to flow. The seep could be effective during a rain-less period of the area in which the seep can actually prolong the stream’s flow by adding water from the groundwater. Aquifer Mud-puddling Puddle Rill Riparian zone restoration Spring Soil mechanics and seepage Meinzer, Oscar E. ed. Hydrology
Atmosphere of Earth
The atmosphere of Earth is the layer of gases, commonly known as air, that surrounds the planet Earth and is retained by Earths gravity. The atmosphere of Earth protects life on Earth by absorbing solar radiation, warming the surface through heat retention. By volume, dry air contains 78. 09% nitrogen,20. 95% oxygen,0. 93% argon,0. 04% carbon dioxide, and small amounts of other gases. Air contains an amount of water vapor, on average around 1% at sea level. The atmosphere has a mass of about 5. 15×1018 kg, the atmosphere becomes thinner and thinner with increasing altitude, with no definite boundary between the atmosphere and outer space. The Kármán line, at 100 km, or 1. 57% of Earths radius, is used as the border between the atmosphere and outer space. Atmospheric effects become noticeable during atmospheric reentry of spacecraft at an altitude of around 120 km, several layers can be distinguished in the atmosphere, based on characteristics such as temperature and composition. The study of Earths atmosphere and its processes is called atmospheric science, early pioneers in the field include Léon Teisserenc de Bort and Richard Assmann.
The three major constituents of air, and therefore of Earths atmosphere, are nitrogen, water vapor accounts for roughly 0. 25% of the atmosphere by mass. The remaining gases are often referred to as gases, among which are the greenhouse gases, principally carbon dioxide, nitrous oxide. Filtered air includes trace amounts of other chemical compounds. Various industrial pollutants may be present as gases or aerosols, such as chlorine, fluorine compounds, sulfur compounds such as hydrogen sulfide and sulfur dioxide may be derived from natural sources or from industrial air pollution. In general, air pressure and density decrease with altitude in the atmosphere, temperature has a more complicated profile with altitude, and may remain relatively constant or even increase with altitude in some regions. In this way, Earths atmosphere can be divided into five main layers, excluding the exosphere, Earth has four primary layers, which are the troposphere, stratosphere and thermosphere. It extends from the exobase, which is located at the top of the thermosphere at an altitude of about 700 km above sea level, to about 10,000 km where it merges into the solar wind.
This layer is composed of extremely low densities of hydrogen and several heavier molecules including nitrogen, oxygen. The atoms and molecules are so far apart that they can travel hundreds of kilometers without colliding with one another, the exosphere no longer behaves like a gas, and the particles constantly escape into space. These free-moving particles follow ballistic trajectories and may migrate in and out of the magnetosphere or the solar wind, the exosphere is located too far above Earth for any meteorological phenomena to be possible
A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Nuclear chemistry is a sub-discipline of chemistry that involves the reactions of unstable. The substance initially involved in a reaction are called reactants or reagents. Chemical reactions are characterized by a chemical change, and they yield one or more products. Reactions often consist of a sequence of individual sub-steps, the elementary reactions. Chemical reactions are described with chemical equations, which present the starting materials, end products. Chemical reactions happen at a characteristic reaction rate at a given temperature, reaction rates increase with increasing temperature because there is more thermal energy available to reach the activation energy necessary for breaking bonds between atoms. Reactions may proceed in the forward or reverse direction until they go to completion or reach equilibrium, Reactions that proceed in the forward direction to approach equilibrium are often described as spontaneous, requiring no input of free energy to go forward.
Non-spontaneous reactions require input of energy to go forward. Different chemical reactions are used in combinations during chemical synthesis in order to obtain a desired product, in biochemistry, a consecutive series of chemical reactions form metabolic pathways. These reactions are catalyzed by protein enzymes. Chemical reactions such as combustion in fire and the reduction of ores to metals were known since antiquity, in the Middle Ages, chemical transformations were studied by Alchemists. They attempted, in particular, to lead into gold, for which purpose they used reactions of lead. The process involved heating of sulfate and nitrate minerals such as sulfate, alum. In the 17th century, Johann Rudolph Glauber produced hydrochloric acid and sodium sulfate by reacting sulfuric acid, further optimization of sulfuric acid technology resulted in the contact process in the 1880s, and the Haber process was developed in 1909–1910 for ammonia synthesis. From the 16th century, researchers including Jan Baptist van Helmont, Robert Boyle, the phlogiston theory was proposed in 1667 by Johann Joachim Becher.
It postulated the existence of an element called phlogiston, which was contained within combustible bodies. This proved to be false in 1785 by Antoine Lavoisier who found the explanation of the combustion as reaction with oxygen from the air
A lava tube is a natural conduit formed by flowing lava which moves beneath the hardened surface of a lava flow. Tubes can be actively draining lava from a volcano during an eruption, or can be extinct, meaning the flow has ceased. Lava tubes are a type of cave formed when an active low-viscosity lava flow develops a continuous and hard crust. Tubes form in one of two ways, by the crusting over of lava channels, and from pāhoehoe flows where the lava is moving under the surface, Lava usually leaves the point of eruption in channels. These channels tend to very hot as their surroundings cool. This means they slowly develop walls around them as the lava cools and/or as the channel melts its way deeper. These channels can get enough to crust over, forming an insulating tube that keeps the lava molten. These types of lava tubes tend to be closer to the eruption point. Farther away from the point, lava can flow in an unchanneled, fanlike manner as it leaves its source. Called pāhoehoe flows, these areas of surface-moving lava cool, forming either a smooth or rough, the lava continues to flow this way until it begins to block its source.
At this point, the lava is still hot enough to break out at a point. Lava flows from the source to this breakout point as the surrounding lava of the pāhoehoe flow cools. This forms a channel that becomes a lava tube. A broad lava-flow field often consists of a lava tube. When the supply of lava stops at the end of an eruption or lava is diverted elsewhere, lava in the system drains downslope. Lava tubes generally have pāhoehoe floors, although this may often be covered in breakdown from the ceiling. A variety of speleothems may be found in lava tubes including a variety of stalactite forms generally known as lavacicles, lavacicles are the most common of lava tube speleothems. Drip stalagmites may form under tubular lava stalactites, and the latter may grade into a known as a tubular lava helictite
Calcium hydroxide, traditionally called slaked lime, is an inorganic compound with the chemical formula Ca2. It is a crystal or white powder and is obtained when calcium oxide is mixed. It has many names including hydrated lime, caustic lime, builders lime, slack lime, Calcium hydroxide is used in many applications, including food preparation. Limewater is the name for a saturated solution of calcium hydroxide. Calcium hydroxide is insoluble in water, with a solubility product Ksp of 5.5 × 10−6.4. Calcium hydroxide solutions can cause chemical burns, at high pH value, its solubility drastically decreases. This behavior is relevant to cement pastes, Ca2 → CaO + H2O Calcium hydroxide adopts a polymeric structure, as do all metal hydroxides. The structure is identical to that of Mg2, i. e. the cadmium iodide motif, strong hydrogen bonds exist between the layers. Calcium hydroxide is produced commercially by treating lime with water, CaO + H2O → Ca2 In the laboratory it can be prepared by mixing solutions of calcium chloride.
The mineral form, portlandite, is rare but can be found in some volcanic, plutonic. It has known to arise in burning coal dumps. CaOH has been detected in the atmosphere of S-type stars, one significant application of calcium hydroxide is as a flocculant, in water and sewage treatment. It forms a fluffy charged solid that aids in the removal of particles from water. This application is enabled by the low cost and low toxicity of calcium hydroxide and this conversion is part of the causticizing step in the Kraft process for making pulp. In Spanish, calcium hydroxide is called cal, corn cooked with cal becomes hominy, which significantly increases the bioavailability of niacin, and it is considered tastier and easier to digest. In chewing coca leaves, calcium hydroxide is usually chewed alongside to keep the alkaloid stimulants chemically available for absorption by the body, Native Americans traditionally chewed tobacco leaves with calcium hydroxide derived from burnt mollusk shells to enhance the effects.
It has used by some indigenous American tribes as an ingredient in yopo. Calcium hydroxide is added to a bundle of areca nut
Deposition is the geological process in which sediments and rocks are added to a landform or land mass. Deposition can refer to the buildup of sediment from organically derived matter or chemical processes, for example, chalk is made up partly of the microscopic calcium carbonate skeletons of marine plankton, the deposition of which has induced chemical processes to deposit further calcium carbonate. Similarly, the formation of coal begins with deposition of material, mainly from plants. The null-point hypothesis explains how sediment is deposited throughout a shore profile according to its grain size and this is due to the influence of hydraulic energy, resulting in a seaward-fining of sediment particle size, or where fluid forcing equals gravity for each grain size. The concept can be explained as sediment of a particular size may move across the profile to a position where it is in equilibrium with the wave, figure 1 illustrates this relationship between sediment grain size and the depth of the marine environment.
The relatively strong onshore stroke of the forms a eddy or vortex on the lee side of the ripple, provided the onshore flow persists. Where there is symmetry in ripple shape the vortex is neutralised and this creates a cloudy water column which travels under tidal influence as the wave orbital motion is in equilibrium. R is the radius of the object, ρ is the mass density of the fluid, g is the gravitational acceleration, Cd is the drag coefficient. When the fluid becomes more viscous due to grain sizes or larger settling velocities, prediction is less straight forward. Cohesion of sediment occurs with the grain sizes associated with silts and clays. Akaroa Harbour is located on Banks Peninsula, New Zealand and this research shows conclusive evidence for the null point theory existing on tidal flats with differing hydrodynamic energy levels and on flats that are both erosional and accretional. Kirby R. Cheniers can be found at any level on the foreshore and this is because sediment grain size analysis throughout a profile allows inference into the erosion or accretion rates possible if shore dynamics are modified.
Planners and managers should be aware that the environment is dynamic. Cementation Cross-bedding Drift Flocculation Longshore drift Overbank Sedimentary rock Sedimentary structures Settling Shields parameter Stokes law Superficial deposits
Sea ice arises as seawater freezes. Because ice is less dense water, it floats on the oceans surface. Sea ice covers about 7% of the Earth’s surface and about 12% of the world’s oceans. Much of the sea ice is enclosed within the polar ice packs in the Earths polar regions, the Arctic ice pack of the Arctic Ocean. Polar packs undergo a significant yearly cycling in surface extent, a natural process upon which depends the Arctic ecology, due to the action of winds and temperature fluctuations, sea ice is very dynamic, leading to a wide variety of ice types and features. Sea ice may be contrasted with icebergs, which are chunks of ice shelves or glaciers that calve into the ocean, depending on location, sea ice expanses may incorporate icebergs. Sea ice does not simply grow and melt, during its lifespan, it is very dynamic. Due to the action of winds, water temperature. Sea ice is classified according to whether or not it is able to drift, Sea ice can be classified according to whether or not it is attached to the shoreline.
If attached, it is called landfast ice, or more often and unlike fast ice, drift ice occurs further offshore in very wide areas, and encompasses ice that is free to move with currents and winds. The physical boundary between fast ice and drift ice is the fast ice boundary, the drift ice zone may be further divided into a shear zone, a marginal ice zone and a central pack. Drift ice consists of floes, individual pieces of sea ice 20 metres or more across, the term pack ice is used either as a synonym to drift ice, or to designate drift ice zone in which the floes are densely packed. The overall sea ice cover is termed the ice canopy from the perspective of submarine navigation, another classification used by scientists to describe sea ice is based on age, that is, on its development stages. These stages are, new ice, young ice, first-year, new ice is a general term used for recently frozen sea water that does not yet make up solid ice. It may consist of ice, slush, or shuga. Other terms, such as ice and pancake ice, are used for ice crystal accumulations under the action of wind.
Nilas designates a sea ice crust up to 10 centimetres in thickness and it bends without breaking around waves and swells. Nilas can be subdivided into dark nilas – up to 5 centimetres in thickness and very dark
Water is a transparent and nearly colorless chemical substance that is the main constituent of Earths streams and oceans, and the fluids of most living organisms. Its chemical formula is H2O, meaning that its molecule contains one oxygen, Water strictly refers to the liquid state of that substance, that prevails at standard ambient temperature and pressure, but it often refers to its solid state or its gaseous state. It occurs in nature as snow, ice packs and icebergs, fog, aquifers, Water covers 71% of the Earths surface. It is vital for all forms of life. Only 2. 5% of this water is freshwater, and 98. 8% of that water is in ice and groundwater. Less than 0. 3% of all freshwater is in rivers and the atmosphere, a greater quantity of water is found in the earths interior. Water on Earth moves continually through the cycle of evaporation and transpiration, precipitation. Evaporation and transpiration contribute to the precipitation over land, large amounts of water are chemically combined or adsorbed in hydrated minerals.
Safe drinking water is essential to humans and other even though it provides no calories or organic nutrients. There is a correlation between access to safe water and gross domestic product per capita. However, some observers have estimated that by 2025 more than half of the population will be facing water-based vulnerability. A report, issued in November 2009, suggests that by 2030, in developing regions of the world. Water plays an important role in the world economy, approximately 70% of the freshwater used by humans goes to agriculture. Fishing in salt and fresh water bodies is a source of food for many parts of the world. Much of long-distance trade of commodities and manufactured products is transported by boats through seas, lakes, large quantities of water and steam are used for cooling and heating, in industry and homes. Water is an excellent solvent for a variety of chemical substances, as such it is widely used in industrial processes. Water is central to many sports and other forms of entertainment, such as swimming, pleasure boating, boat racing, sport fishing, Water is a liquid at the temperatures and pressures that are most adequate for life.
Specifically, at atmospheric pressure of 1 bar, water is a liquid between the temperatures of 273.15 K and 373.15 K
Lava is the molten rock expelled by a volcano during an eruption. The resulting rock after solidification and cooling is called lava. The molten rock is formed in the interior of planets, including Earth. The source of the heat melts the rock within the earth is geothermal energy. When first erupted from a vent, lava is a liquid usually at temperatures from 700 to 1,200 °C. A lava flow is an outpouring of lava, which is created during a non-explosive effusive eruption. When it has stopped moving, lava solidifies to form igneous rock, the term lava flow is commonly shortened to lava. Although lava can be up to 100,000 times more viscous than water, lava can flow great distances before cooling and solidifying because of its thixotropic, explosive eruptions produce a mixture of volcanic ash and other fragments called tephra, rather than lava flows. The word lava comes from Italian, and is derived from the Latin word labes which means a fall or slide. The first use in connection with extruded magma was apparently in an account written by Francesco Serao on the eruption of Vesuvius between May 14 and June 4,1737.
Serao described a flow of lava as an analogy to the flow of water. The composition of almost all lava of the Earths crust is dominated by silicate minerals, mostly feldspars, pyroxenes, micas, igneous rocks, which form lava flows when erupted, can be classified into three chemical types, felsic and mafic. These classes are primarily chemical, the chemistry of lava tends to correlate with the temperature, its viscosity. Felsic or silicic lavas such as rhyolite and dacite typically form lava spines, most silicic lava flows are extremely viscous, and typically fragment as they extrude, producing blocky autobreccias. Felsic magmas can erupt at temperatures as low as 650 to 750 °C, unusually hot rhyolite lavas, may flow for distances of many tens of kilometres, such as in the Snake River Plain of the northwestern United States. Intermediate or andesitic lavas are lower in aluminium and silica, and usually somewhat richer in magnesium, intermediate lavas form andesite domes and block lavas, and may occur on steep composite volcanoes, such as in the Andes.
Poorer in aluminium and silica than felsic lavas, and commonly hotter, greater temperatures tend to destroy polymerized bonds within the magma, promoting more fluid behaviour and a greater tendency to form phenocrysts. Higher iron and magnesium tends to manifest as a darker groundmass, mafic or basaltic lavas are typified by their high ferromagnesian content, and generally erupt at temperatures in excess of 950 °C