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Greenhouse A greenhouse is a structure with a glass or plastic roof and frequently glass or plastic walls; it heats up because incoming visible solar radiation from the sun is absorbed by plants, soil, and other things inside the building. Glass is transparent to this radiation. The warmed structures and plants inside the greenhouse re-radiate this energy in the infra-red, to which glass is opaque, and that energy is trapped inside the glasshouse. Although there is some heat loss due to conduction, there is a net increase in energy (and therefore temperature) inside the greenhouse.

Air warmed by the heat from hot interior surfaces is retained in the building by the roof and wall. These structures range in size from small sheds to very large buildings.

Greenhouses can be divided into glass greenhouses and plastic greenhouses. Plastics mostly used are PEfilm and multiwall sheet in PC or PMMA. Commercial glass greenhouses are often high tech production facilities for vegetables or flowers. The glass greenhouses are filled with equipment like screening installations, heating, cooling, lighting and may be automatically controlled by a computer. The glass used for a greenhouse works as a barrier to air flow and its effect is to trap energy within the greenhouse, which heats both the plants and the ground inside it. This warms the air near the ground, and this air is prevented from rising and flowing away.

This can be demonstrated by opening a small window near the roof of a greenhouse: the temperature drops considerably. This principle is the basis of the autovent automatic cooling system. A miniature greenhouse is known as a cold frame.


Greenhouses protect crops from too much heat or cold, shield plants from dust storms and blizzards, and help to keep out pests. Light and temperature control allows greenhouses to turn inarable land into arable land, thereby improving food production in marginal environments.Because greenhouses allow certain crops to be grown throughout the year, greenhouses are increasingly important in the food supply of high latitude countries. One of the largest greenhouse complexes in the world is in Almeria, Spain, where greenhouses cover almost 50,000 acres (200 km2).

Sometimes called the sea of plastics.Greenhouses are often used for growing flowers, vegetables, fruits, and tobacco plants. Bumblebees are the pollinators of choice for most greenhouse pollination, although other types of bees have been used, as well as artificial pollination. Hydroponics can be used in greenhouses as well to make the most use of the interior space.

Besides tobacco, many vegetables and flowers are grown in greenhouses in late winter and early spring, and then transplanted outside as the weather warms. Started plants are usually available for gardeners in farmers' markets at transplanting time. Special greenhouse varieties of certain crops such as tomatoes are generally used for commercial production.


Cucumbers reached to the ceiling in a greenhouse in Richfield, Minnesota, where market gardeners grew a wide variety of produce for sale in Minneapolis. ca. 1910 19th Century Orangerie in Weilburg, Germany The idea of growing plants in environmentally controlled areas has existed since Roman times. The Roman emperor Tiberius ate a cucumber-like[2] vegetable daily. The Roman gardeners

used artificial methods (similar to the greenhouse system) of growing to have it available for his table every day of the year. Cucumbers were planted in wheeled carts which were put in the sun daily, then taken inside to keep them warm at night.[3] The cucumbers were stored under frames or in cucumber houses glazed with either oiled cloth known as "specularia" or with sheets of selenite (a.k.a. lapis specularis), according to the description by Pliny the Elder.

The first modern greenhouses were built in Italy in the thirteenth century[5] to house the exotic plants that explorers brought back from the tropics. They were originally called giardini botanici (botanical gardens).

The concept of greenhouses soon spread to the Netherlands and then England, along with the plants. Some of these early attempts required enormous amounts of work to close up at night or to winterize.

There were serious problems with providing adequate and balanced heat in these early greenhouses. The French botanist Charles Lucien Bonaparte is often credited with building the first practical modern greenhouse in Leiden, Holland to grow medicinal tropical plants. Originally on the estates of the rich, with the growth of the science of botany greenhouses spread to the universities. The French called their first greenhouses orangeries, since they were used to protect orange trees from freezing.

As pineapples became popular pineries, or pineapple pits, were built. Experimentation with the design of greenhouses continued during the Seventeenth Century in Europe as technology produced better glass and construction techniques improved.

The greenhouse at the Palace of Versailles was an example of their size and elaborateness; it was more than 500 feet long, 42 feet wide, and 45 feet high.

In the nineteenth Century the largest greenhouses were built. The conservatory at Kew Gardens in England is a prime example of the Victorian greenhouse. Although intended for both horticultural and non-horticultural exhibition these included London's Crystal Palace, the

New York Crystal Palace and Munich’s Glaspalast. Joseph Paxton, who had experimented with glass and iron in the creation of large greenhouses as the head gardener at Chatsworth, in Derbyshire, working for the Duke of Devonshire, designed and built the first, London's Crystal Palace.

A major architectural achievement in monumental greenhouse building were the Royal Greenhouses of Laeken (1874-1895) for King Leopold II of Belgium. In Japan, the first greenhouse was built in 1880 by Samuel Cocking, a British merchant who exported herbs.

In the Twentieth Century the geodesic dome was added to the many types of greenhouses. A notable example is the Eden Project, in Cornwall. Greenhouse structures adapted in the 1960s when wider sheets of polyethylene film became widely available. Hoop houses were made by several companies and were also frequently made by the growers themselves. Constructed of aluminium extrusions, special galvanized steel tubing, or even just lengths of steel or PVC water pipe, construction costs were greatly reduced. This meant many more greenhouses on smaller farms and garden centers.

Polyethylene film durability increased greatly when more effective inhibitors were developed and added in the 1970s. These UV inhibitors extended the usable life of the film from one or two years up to 3 and eventually 4 or more years. Gutter connected greenhouses became more prevalent in the 1980s and 1990s.

These greenhouses have two or more bays connected by a common wall, or row of support posts. Heating inputs were reduced as the ratio of floor area to roof area was increased substantially. Gutter connected greenhouses are now commonly used both in production and in situations

where plants are grown and sold to the public as well. Gutter connected greenhouses are commonly covered with a double layer of polyethylene film with air blown between to provide increased heating efficiencies, or structured polycarbonate materials.

Greenhouse effect by Max Rutherford Posted on November 21st 2009 The greenhouse effect is a term that is commonly used to refer to the atmosphere’s impact upon the world environment and the warming effect it has on the planet as a whole. This can include both the detrimental aspects that are a result of modern-day global warming as well as the natural changes the planet faces throughout the centuries. To look at this in greater detail let’s first break down the greenhouse effect into two main categories: the natural benefits of the greenhouse effect upon the planet and the potential negative aspects that are being caused recently and have given rise to growing concerns.

How the Greenhouse Effect Helps Us In order to fully understand how the greenhouse effect has an impact upon us it is first important to understand what the greenhouse effect really is. The term “greenhouse effect� has been coined in order to refer to the natural occurrence that results from special gases collecting in the atmosphere that retain the heat on the planet that is generated from either the sun or some other source –- much like a greenhouse naturally retains heat and moisture to assist with plant growth. This effect was first discovered in the 1800s though not fully verified or experimented upon and explored until nearly the 1900s came round.

Its is a naturally occurring instance that is intensified by various man-made emissions that helps regulate planetary heat by retaining some amount while allowing other heat to be radiated into space for dispersal. Though it may be surprising to many people who have heard the greenhouse effect discussed quite openly on the news and other sources these days the greenhouse effect can actually have as much of a positive impact upon the world as it can a negative one. In fact, virtually all aspects of the greenhouse effect are more beneficial than not due to its impact upon the world ecology in general.

What this means is that rather than being a detrimental aspect that is killing the planet the greenhouse effect is actually responsible for giving rise to much of the life that his present around the world and helps support all species in their development.

The reason for the greenhouse effects beneficial aspects to the planet primarily center around the fact that the greenhouse effect allows for the average temperature of the earth to maintain a solid higher level than it would otherwise. By successfully retaining heat within the atmosphere rather than allowing it to disperse completely the Earth’s average ground temperature can be maintained at a steady 14°C (or 57°F) — a much warmer temperature and the otherwise probable -18°C (or -0.4°F) that is the Earth’s natural “black body” temperature, or temperature without any heat retention by the atmosphere, that would be maintained should be greenhouse effect not be present.

In short, it is because of the greenhouse effect that are able to enjoy the temperate climate that currently exists and allows us to live the way we do today. ould the heat fail to continue being contained within the atmosphere the Earth wound revert to an Ice Age, as has been seen happening throughout the course of the planet’s history via geological studies in places such as Antarctica and other regions. wing Concerns and What They Mean to Us

Although the greenhouse effect is a natural occurring phenomenon that has existed throughout the entire course of the planet’s history there are a number of concerns existing to date over mankind’s impact upon this naturally occurring phenomenon and the possible negative side effects this could have. Through the process of creating additional “greenhouse gas” emissions through industrial and technological developments as well as the reduction of carbon dioxide consuming plants around the world

through massive deforestation’s and general reduction of plant growth through development movements and urban expansion mankind as a whole has had a tremendous impact upon the naturally occurring greenhouse stability of the world. One of the most notable factors that has contributed to the increase in greenhouse gases that are affecting the greenhouse effect worldwide is through the widespread usage of fossil fuels over the past 100 years.

Because of the increased usage of these fuels and a number of other factors mankind has contributed to over 50% of the current levels of carbon dioxide and other greenhouse gases are currently existing in the atmosphere and are causing the Earth’s temperature to increased substantially over time. What this means for us is that by continuing along the same path we have been doing we are running a high risk of causing the delicate temperate climate that currently exists on the planet to shift and therefore potentially have negative and potentially disastrous impacts upon the world as a whole.

The most notable threat of global warming comes in the form of the increased melting of polar ice caps and other freshwater formations around the poles. This melting not only affects the habitats of the wildlife that exists in these areas but also directly affects the ocean currents that are responsible for regulating temperatures in many locations and could have an adverse impact upon the actual climate stabilization worldwide. What this means for us is that at this time unless we can regulate our own emissions to have as minimal effect upon the greenhouse gases as possible and help to stabilize the greenhouse effect that is granting us this temperate climate we may run the risk of adversely affecting worldwide climates and

ecosystems and potentially throw the environment as a whole into a more unstable state that will have drastic repercussions upon all life on the planet as a whole.

It is for this reason that many people around the world have been moving more and more towards alternative forms of energy in order to reduce the level of carbon emissions that are currently being used and are attempting to establish an ecological equilibrium that can balance out the greenhouse gases in order to form a ongoing, stable and functional environment for generations to come. If this can not be achieved in the future it is unknown for certain what may happen, however many experts believe this could contribute to the onset of an ice age or some other disastrous ecological event that could potentially pose a risk to all life as we know it.

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