the Earth's systems

    Earth is warmed by the absorption of visible radiation from the Sun and is cooled by the emission of infrared radiation to space. Much of the infrared radiation by Earth's surface is absorbed and reemitted by atmosphere gases. The result is a greenhouse effect that warms the surface by about 33℃. Without this natural greenhouse effect, Earth would be too cold to support life.
   The driving force for the atmospheric circulation is the global distribution of energy. The angle at which the Sun's ray strike Earth changes from the equator toward the poles, The result is that incoming solar radiation decreases with latitude. More solar radiation is received in the tropics than at the poles, resulting in an equator-pole temperature gradient. The temperature gradient drives the atomosperic circulation because of the inverse relationship between the temperature and the density of a gas: higher temperature produce lower densities. Differences in the distribution of global temperature cause differences in air density and, therefore pressure. Air tend to move from areas of high pressure to areas of low pressure. These large-scal movement of air produce the global wind belts.
    As with the atmosphere, the driving force for the oceanic circulation is the global distribution of energy. Unlike the atmosphere, however, the ocean circulation is driven by indirectly by temperature differences: the surface-ocean circulation is, in fact, driven by the circulation of atmosphere. Due to friction, wind blowing over the ocean surface water along, producing ocean currents. The pattern of surface-ocean currents is modified by the Coriolis effect, a consequence of Earth's rotation, and by the distribution of land and oceans,
   The solid Earth is dynamic, not static. Wegener's idea of drifting continent proposed in the early 20th century has largely been substantiated. New seafloor is created at mid-ocean ridges and moves outward as oceans basins grow. Old seafloor is distorted  at deep-sea trenches in subduction zones. Earthquake outline the surface of the slab of oceanic lithosphere being sub-ducted beneath the continent; their foci along a continental margin become ever deeper away from the trench. Deeper probing of Earth's interior has revealed heterogeneity in composition and temperature that can be the result only of large-scale circulation in the mantle or the outer core.
  There is also the global carbon cycle that occur on land and in oceans and involve both biological and nonbiological chemical reaction on the Earth.
   Some of the characteristics of life that allow it to play an important role in the Earth system are its tendency toward exponential growth, its need for energy, its tendency to pollute, and tis versatility.
   The circulations of the atmosphere, oceans, solid and energy and so on are support the Earth and the life. They are play an important role on the working of the earth.

the early evolution of life

    Hello,  I had a little trouble about my work, and I believe that I can do it well.  How about you?  Do you have troubles? You can tell me. haha  
    Earth is the only planet on which we have confirmed the existence of life, past or present. life originated on Earth as much as 3.9 billion years ago. Three steps must have been accomplished on the way to the complex life forms we know today: (1) chemosynthesis of small organic molecules from inorganic precursors; (2) biosynthesis, the polymerization of small organic molecules to form biopolymers, especially protein; and (3) the development of the complex chemical machinery needed for metabolism and replication. The specific mechanism by which life originated are still hypothetical.
   Life contribute to the chemical evolution of the Earth system through the buildup of oxygen and sequestration of carbon. Oxygenation happened over a long time, but the onset of major oxygenation coincides roughly with the beginning of the Proterozoic Eon. Once the ozone layer began to absorb harmful shortwave radiation, organisms would have been able to survive in shallow waters; this critical stages was reached around 600 million years ago, just before the onset of Phanerozoic Eon. The emerging biosphere had had a profound impact on carbon cycling; limestone and organic sediment provide long-term storage reservoirs for carbon, sequestering it form the atmosphere and hydrosphere.
   The most ancient known fossil are 3.55 billion years old, found in rocks from Archean Eon. Some early fossils are the remains of microscopic procaryotes; others are stromatolites that precipitated as a result of bacteria influencing the chemistry of seawater. The dominated Earth for about 2 billion years, was prokaryotic and anaerobic. Anaerobic cells acquire energy by fermentation, which restricts them to a small size and limits their structural complexity. The first photosynthetic prokaryotes were probably cyanobacteria.
    The first land plants were seedless; these evolved into naked-seed plants, and grasses. Arthropods were probably the first animal to move from sea to land. Pikaia, the first known chordate, was jawless; jawed fish evolved later. The first to venture onto land were crossopterygians, which give rise to amphibians. Amphibians have permeable skins and lack a moist environment for reproduction, and thus  remain dependent on the aquatic environment. Reptiles became liberated form the water by evolving a water-tight skin and an egg with a shell; they evolved into two orders of dinosaurs and two new verterbrate classes__mammals and birds.
    The first clearly bipedal hominid was Australopithecus, whose fossils range from about 3.9 to 3.0 million years in age. Fossil of Homo erectus, possibly the first spices of our own genus, dates to about 1.8 million years ago. Homo erectus disappeared 300,000 years ago and was replaced by Homo neanderthalensis, The poor fossil record between 400,000 and 100,000 years ago has made it difficult for scientists to determine how the transition occurred, but DNA studies suggest that Homo sapiens is not a direct descendant of Neanderthals. The Neanderthals disappeared about 30,000 years ago and were replaced by the first indisputable members of our own species, Homo sapiens.
    About 99 percent of the species that have lived on Earth are now extinct. Extinction is a natural process, but it has not happened at a constant rate over geologic time. Superimposed on background extinctions are at least five major mass extinction events, in which many types of organisms died out over short periods. These may have been caused by climatic and other environmental changes, possibly accelerated by major meteorite impacts, massive episodes of volcanism, or the formation of supercontinents. Humans have greatly accelerated the rate of extinction of species.






    

Natural and environmental hazard

    Hello, how about your work today? how about your study today?
    I'm fine,but a small earthquake was happened yesterday. I think some natural hazards like earthquake are occur on the earth anytime. Today I will talk about the geologic hazards on the earth.  
   A geologic hazard is a natural geologic event that can endanger human lives and threaten human property. Earthquakes, geomagnetic storms, landslides, sinkholes, tsunamis, and volcanoes are all types of geologic hazards.
   Earthquakes occur all over the world and often occur without significant warning. These geohazards can have far-reaching affects on humans and on the surface of the Earth. Small, localized earthquakes may cause no noticeable damage and may not even be felt by people living in the affected area. In contrast, a large earthquake may cause destruction over a wide area and be felt thousands of miles away.Earthquakes can also occur within plates, although plate-boundary earthquakes are much more common. Less than 10 percent of all earthquakes occur within plate interiors. As plates continue to move and plate boundaries change over geologic time, weakened boundary regions become part of the interiors of the plates. These zones of weakness within the continents can cause earthquakes in response to stresses that originate at the edges of the plate or in the deeper crust. The New Madrid earthquakes of 1811-1812 and the 1886 Charleston earthquake occurred within the North American plate.While we can't prevent earthquakes or even accurately predict when they will occur,but what we should to know is how to be prepared for an earthquake and what to do if one occurs.
    A landslide is the movement of soil, rock, or other earth materials, downhill in response to gravity. Landslides include rock falls and topples, debris flows and debris avalanches, earthflows, mudflows, creep, and lateral spread of rock or soil. Landslides constitute a major geologic hazard, they are widespread, occurring in all 50 States, and they cause more than $2 billion in damages and more than 25 fatalities on average each year.One of the largest landslides in the world is in the 20th century occurred at Mount St. Helens, Washington, in 1980. A moderate earthquake caused roughly 1.7 cubic miles of rocks and mud to break free and slide down the side of the volcano, releasing pent-up pressure to produce the major eruption of May 18.
  A volcano is a vent at the Earth's surface through which magma and associated gases erupt, and also the cone built by eruptions. A volcano that is currently erupting or showing signs of unrest (earthquakes, gas emissions) is considered active. A volcano that is not currently active but which could become active again is considered dormant. Extinct volcanoes are those considered unlikely to erupt again. Volcanic eruptions are one of Earth's most dramatic and violent agents of change. They pose significant geologic hazards because their eruptions and associated activities can affect large areas and go on for extended periods of time. Many kinds of volcanic activity can endanger the lives of people and property, and the affects of these activities are felt both close to and far away from the volcano. Explosive eruptions can spread lava, gas and other materials over a wide area, and may drastically alter the landscape. Slow eruptions or flows can also alter landscapes, while associated earthquakes, atmospheric effects, landslides, and floods all may damage or destroy property and threaten human lives.
   Tsunamis are large, destructive waves that are caused by the sudden movement of a large area of the sea floor. Most tsunamis are caused by earthquakes, some are caused by submarine landslides, a few are caused by submarine volcanic eruptions and on rare occasions they are caused by a large meteorite impact in the ocean.The Krakatau volcanic eruption of 1883 generated giant waves reaching heights of 125 feet above sea level, killing thousands of people and wiping out numerous coastal villages. Locally generated tsunamis may reach a shoreline with only a few minutes warning, while distant events may allow several hours warning. In addition, many coastal areas have tsunami alert systems that sound sirens or provide information through local media. While we can't prevent tsunamis, we can take steps to lessen their impact. Those who live in or visit tsunami-prone areas should know the warning signs of an approaching tsunami, and what to do when a tsunami is imminent.
  We live on the earth which has too many natural and environmental hazards, and here I just have talked some. Also, hazards like flood, Glossary of Terms and Sinkholes can't be looked down upon.
   We can't change the natural hazard, but we can change the man-made hazard what we do on the earth. Before we protect our lives, we should protect the Earth. If we save the food and water, if we protect the rare species of animals, plants and other living things, the earth will be better, we will be live longer.

ice age on the earth

 hello, today is also a good day! don' t you think so? if NO, just hope tomrrow will be a better day!

  do you see the movies<Ice Age>?
  I like snow, but I can't image that the earth became a ice ball. can you?  So I think the earth in the ice age is the same in those movies, but not so many lovely animals.
   The Ice Age, which began about 2 million years ago, was very complex period characterized by a number of advances and with drawals of glacial ice. Most of the major glacial episodes occured during a division of the geologic time scale called  the pleistocene epoch. Perhaps the most convincing evidence for the occurrence of several glacial avdances during the Ice Age is the widespread existence of multiple layers of drift and un uniterrupted record of climate cycles perserved in seafloor sediments.
   Any theory that attempts to explain the cause of glacial ages must answer two basic questions:(1) What cause the onset of glacial condition? and (2) What cause the alternating glacial and interglacial stages that have been documented for the pleistocene epoch? Two of the many hypotheses for the cause of glacial ages involve (1) plate tectonics and (2) variation in Earth's orbit. Other factors that related to climate change during glacial ages include: change in atmospheric composition, variation in the amount of snnlight reflected by Earth's surface, and changes ocean circulation.
    Therefor, I will inrtoduce the glacier.
   
   
    A glacier is a thick mass of ice originating on land as a result of the compaction and recrystallization of snow, and it shows evidence of past and present flow. Today, vally or alpine glacier are found in mountain areas where they usually follow vallys that were originally accupied by steams. Ice sheets exist on a much larger scale, covering most of Greenland and America. In addition, covering some upland and plateaus are masses of glacial ice called ice caps. they occur in many places, including Iceland, and several of the large island in the Artic Ocean. Piedmont glacier occupy broad lowland at the bases of steep mountains and form when one or more alpine glaciers merge from the confining walls of mountain valleys.
   The average velocity of glacial movement is generally quite slow but varies considerably from one glacier to another. The advance of some glacier is characterized by periods of extremly rapid movement called surges.
   Any sediment of glacial origin is called drift. The two distinct types of glacial drift are (1)till, which is unsorted sediment deposyed directly by the ice; and (2) stratified drift, which is relatively well-sorted sediment laid down by the glacial meltwater. Also, landforms made of sratified drift.

   In addition to massive erosional and depositional work, other effects of Ice Age glacier include the forced migration of organism, changes in steam courses, formation of large proglacial lakes, adjustment of the crust by rebounding after the remorval of the immense load of ice, and climate changes caused by the existence of glaciers themselves. In the sea, the most far-reaching effect of the Ice Age was the worldwide change in the sea level that accompained each advance and retreat of the ice sheets.
    Today glaciers cover nearly 10 percent of Earth'land surface; however, in the recent geologic past, ice sheets were three times more extensive, covering vast areas with ice thousands of meters thick. So what make them disappeared? The global warming, or the pollutions, or some other thing? how do you think about it?
    we should know everything that on the earth to make our life better and live longer.

   

Earth's resources

 where does the clothes come from? where does the gus come from? where does the food come from?
  I thought that they are not made but be on the earth before. I'm wrong. some are made by human,and some are produced by the Earth. So what are the Earth's resources?  you will know by reading this blog.
   Resources are commonly divided into two broad categories_ renewable and nonrenewable. Renewable resources can be replenished over relatively short time spans. Example include natural fibers for clothing and tree for lumber. Nonrenewable resources form so slowly that, form a human standpoint, Earth contains fixed supplies. Example include fuels such as oil and coal, and metal such as copper and gold. A rapidly growing world population and the desire for an improved living standard are causing nonrenewable resources to become depleted at an increasing rate.
   Coal, petroleum, and natural gas, the fossil fuels of  our modern economy, are all associated with sedimentary rocks. Coal originates from large quantities of plant remain that assumulate in an oxygen-deficient environment, such as swamp. More than 70 percent of present-day coal usage is for the generation of electricity. Air pollution by the sulfur oxide gases that form from burning burning most types of coal is a significant environment problem.
   Oil and natural gas, which commonly occur together in the pore spaces of some sedimentary rocks, consist of various hydrocarbon compounds(compounds made of hydrogen and carbon mixed together). petroleum formation is associated with the accumulation of sediment in ocean areas that are rich in plants and animal remains that becaome buried and isolated in an oxygen-deficient environment. When conventional petroleum resources are no longer adequate, fuels derived from oil sand and oil shale may become subsititues. Presently, oil sands form the province of Alberta are a sinificant contributor to Canada's oil produce.
 

    Mineral resources are the endowment of useful mineral ultimately available commerially. Resources inlcude already idenfied deposits from which minerals can be extracted profitably, called reserves, as well as know deposits that are not yet economically or technologically recoverable. Deposits inferred to exist but not yet discovered are also considered mineral resources. The term ore is used to denote those useful metallic minerals that can be mined for a profit, as well as some nonmetallic minerals, such as fluorite and sulfur, that contain useful substances.
 




     How long can our remaining resources sustain the rising standard of living in today's countries and still provide for the growing needs of developing regions? How much environmental deterioration are we willing to accept in pursuit of resources? Can alternatives be found? If we want to live longer and longer, we should to understand our resources and their limits.

the study of landforms

   Before I talk about the landforms, you can watch the vedio. It can make you understand easily.

   We all familar with the magificent array of scenry on Earth's surface. It varies from the ice-covered to dry desert to teamy jungles. Geomorphology is the study of the varied landforms on the surface of the Earth, which I will talk about.
   Three primary influences affect the type of scenery that may be produced at a given point on Earth's surface. The first is the local geology_the type of rocks and structures that make up the land. The second is the local climate, cliamte varies with latitude; it is warm and wet the equator and cold and dry at the poles. Climate also varies as a result of atmospheric circulation. Time is the third major influence on landforms. Earth's contients are moved around on teconic plates, slowly changing position on the surface of globe. Accrodingly, the local climate will change with the time, and so well the landscapes that are formed. In a wod, Landforms are controlled by the local geology and climate,and by time.
   Before examing different geomorphologic environments, we must explore the role of gravity(mass wasting) and running water(the hydrologic cycle) in shaping the planet's surface.

    Mass wasting refers to the downslope movement of rock, regolith, and soil under the direct influence of gravity. In the evolution of the most landforms, mass wasting is the step that follows weathering. The combined effects of mass wasting and erosion by running water produce stream valleys.
   The hydrologic cycle describs the continuous interchange of water among the oceans, atmosphere, and continents. Powered by energy from the Sun, it is a global system in which the atmosphere provide the link between the oceans and continents. The processes involved the hydrologic cycle include precipitation, evaporation, infiltration(the movement of water into rocks or soils through cracks and pore spaces), runoff(water that flows over the land), and transpiration(the release of water wapor to the atmosphere by plants). Running water is the most important agent sculpting Earth's surface.
      Now the following will examine landforms.
      One of the most common landforms is valley. This feature is carried by small steams and rivers, and take a wide variety of forms_ from wide broad plains, such as the Grand Canyon of the Calorado River. The shape of a river valley depends on many factors such as the cliamte, the slope of the land surface, and the nature of soil or rock over which the river flows. The valley will change both in location and with time. In a mountain valley, a glacier can be likened to a river of ice. Like a river of water,it starts high in the mountains where snow collects and is changed into denser ice.
     As with the glacial envrionment, the desert environment is defined by climate. The scarcity of water that serves to define desert regions gives rise to unique landforms, although the basic principles of erosion, sediment transport, and diposition are the same in desert as anywhere on the continents.
       A desert is a part of the world that is literally deserted because of extremes in the environment. Although we may think of desert as being hot or sunny, desert regions are principally characterized by low rainfall. Most of the desert of the world are located in two belts adjacent to the tropic at 30°N and 30°S of the equator. These are regions that receive little rainfall owing to their location on the downflowing limits of atmosphere circulation cells. Desert conditions can also be caused by rainshadow effects.
   Coastlines are a dynamic interface between land and sea. They change position and form through time. On the time scale of single year, the coast at one location can vary from being barren of sediment to forming a sandy beach. Over shousands of years, shorelines have moved inland or regressed from land by several kilometers. The two main agents responsition along coasts are waves and tides. Tides are caused by the gravitational pull of the Sun and especially the Moon. Waves expend their energy by breaking, and the surf is an important agent of coastal erosion and transport.
    As we know, the Earth has many landforms,so I can't write all the forms in my blog. The surface of the Earth is changing slowly by the time, what the earth will be like after thousands of years? Can you image that? No, I can't.
   Hope you can feel the huge of the earth.
   

movement in space

 How do you think the radio? if you see that, you will know the Earth more.

 today I will talk about the Earth of the movement in space.
Three facts about the earth's motions are of vital consequence in the princeples of the earth science: first, that the earth turns on an axis, a motion always called ratation; second ., the axis of ratation is inclinned at a constant angle with respect to the plane of the earth's orbit, or plane of the ecliptic; third, that the orientation of the earth's axis in space with respect to the stars holds nearly constant.
   Earth's rotation is the rotation of the solid Earth around its own axis. The Earth rotates towards the east. As viewed from the North Star Polaris, the Earth turns counter-clockwise.
The North Pole, also known as the Geographic North Pole or Terrestrial North Pole is the point in the Northern Hemisphere where the Earth's axis of rotation meets its surface. This is a different point than the Earth's North Magnetic Pole. The South Pole is the other point where the Earth's axis of rotation intersects its surface, in Antarctica.
The Earth rotates once in about 24 hours from the point of view of the sun and once every 23 hours 56 minutes and 4 seconds from the point of view of the stars (see below). Earth's rotation is slowing slightly with time; thus, a day was shorter in the past. This is due to the tidal effects the Moon has on Earth's rotation. Atomic clocks show that a modern day is longer by about 17 milliseconds than a century ago, slowly increasing the rate at which UTC is adjusted by leap second

In astronomy, the Earth's orbit is the motion of the Earth around the Sun, from an average distance of approximately 150 million kilometers away. A complete orbit of the earth around the Sun occurs every 365.256363 mean solar days (1 sidereal year)^. This motion gives an apparent movement of the Sun with respect to the stars at a rate of about 1°/day (or a Sun or Moon diameter every 12 hours) eastward, as seen from Earth. On average it takes 24 hours—a solar day—for Earth to complete a full rotation about its axis relative to the Sun so that the Sun returns to the meridian. The orbital speed of the Earth around the Sun averages about 30 km/s (108,000 km/h), which is fast enough to cover the planet's diameter (about 12,700 km) in seven minutes, and the distance to the Moon of 384,000 km in four hours.
 So this blog is difficult to write.I don't know the movement of the earth very well. But I want to know how can the earth move in the sapce .
 The movement of the earth creat the time and the season,so we can see the flower or the snow by diffierent seasons,and we can live by death and bron. I think is magical.