Before moving to how a greenhouse works let’s have an idea of what is a greenhouse. Basically, we are using greenhouses to plant during the winter season. In other words, it is a forcing structure for plants to grow. It allows plants to grow naturally by creating a favorable artificial environment. The plants inside a greenhouse grow regardless of the Season, Weather, or Climate outside. We hear that earth is having a greenhouse effect and global warming happens. At the end of this article, you will understand how a greenhouse works and what is the greenhouse effect.
A greenhouse uses transparent or in some cases translucent plastic or glass sheets for roofs and walls. These sheets allow sunlight rays to enter the structure. Then plants absorb them and convert them into heat energy. When the plant releases the heat, the emitted heat is trapped inside the structure. The greenhouse will stay heated in this way. This heated environment is very suitable for a plant to grow. The structure has vents or fans to prevent it from getting too hot. Likewise, a greenhouse creates a favorable environment for plant growth.
How does a greenhouse work
The easiest explanation is converting light energy from the sun into heat energy and trapping it inside a structure. But this is not simple as it seems, it requires some hard work. When we are on the beach we can feel the sunburn from sunlight. When sunlight hit on an opaque surface, the surface will absorb the heat or energy from the light rays. But this surface does not emit that energy back instantly. It releases the heat gradually. So the heat energy retains for a certain time. In a greenhouse, the opaque surfaces are the plant and floor, it absorbs heat and releases it gradually. The plastic walls and roof are good at transmitting light but not heat. This results in heating the atmosphere inside the structure for a long time.
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Controlling the temperature inside the greenhouse
Plants favor a certain temperature, but when the temperature rises above this certain temperature, it is bad for the plant’s growth and sometimes plants will die. Another effect is when the temperature is high, water in the soil will evaporate quickly. This results in drying up the soil and increasing the relative humidity inside the greenhouse. To control this, vents or in some cases fans are used. These vents allow heated air to escape from the greenhouse. The temperature is kept steady with the help of vents and fans. In some greenhouses, these are working automatically while in others a person is responsible for maintaining a steady temperature. He will open and close the vents accordingly to keep a certain temperature.
Now, you may be wondering how to maintain a greenhouse on cloudy days. The answer is by using heaters. Yes, greenhouses use heaters to maintain the temperature on cloudy days and when it is difficult to achieve the required temperature.
Greenhouse Effect on Earth
In a greenhouse plastic walls and roofs prevents the heat from escaping. Likewise on Earth greenhouse gases such as Carbon Dioxide, Methane, Nitrous oxide, and water vapor will absorb heat and rise up in the atmosphere. When more and more gas comes, the concentration of these greenhouse gases will increase in the upper atmosphere. This concentrated gas mixture act as a barrier like the walls of a greenhouse. This gas barrier allows sunrays to enter the atmosphere. But it does not allow the heat to escape through the gas barrier. Only reflecting light rays will pass through the barrier. This will result in the heat staying in the atmosphere and hence the temperature will increase. Then global warming will occur.
So the greenhouse effect has its uses as well as disadvantages. If we can control the greenhouse effect like in the greenhouse, there is no problem. But when it comes to the global level we are out of options. Let’s hope that science gives us a solution soon.
Interested in building your own greenhouse? Read your article on How to build your own greenhouse
