Design and physical principles of greenhouse functioning
How does a greenhouse work? After all, you see, it is somewhat unreasonable to use any device without having an idea how it works at least at a basic level. Understanding the principle of operation of the greenhouse, you will be able to use its capabilities to the maximum, with maximum efficiency. From the simplest home-made film greenhouses to the complex industrial luxury greenhouse complexes, they all operate on the basis of the same basic principles.
How a greenhouse works
The greenhouse is based on simple principles of physics – thermal radiation and heat transfer. The greenhouse collects the thermal radiation coming from the outside, turns it into heat and stores this heat. This allows you to keep a certain stable temperature inside the greenhouse, creating the most favorable environment for the growth and vital activity of horticultural crops.
In addition, the greenhouse protects both from the effects of the external environment – for example, such weather conditions as wind, hail or snow, and from pests – beetles, locusts and domestic animals that your crops can trite to eat or trample.
Getting warm in the greenhouse
The main task of the greenhouse is to utilize the thermal radiation received from the outside from the sun’s rays and / or artificial sources. Inside the walls of the greenhouse, thermal radiation is converted into heat, heating the greenhouse from the inside.
You can feel the same effect yourself by closing all the windows inside the car on a summer day. Even if you do not start the engine, after just a few minutes, the temperature inside the cabin will become noticeably higher than outside – this is the sunlight that has heated the insides of your cabin, and this heat cannot go anywhere.
The materials a greenhouse is made of also affect the ability to retain heat and regulate the temperature inside the greenhouse. For example, polycarbonate is excellent as a greenhouse material due to its high coefficient of thermal expansion and high heat resistance.
The greenhouse is a sealed room, and this makes it impossible for air to circulate between the inside of the greenhouse and the environment.
Air circulation equalizes the temperature difference, which would negate the main function of the greenhouse – maintaining a stable temperature, independent of the temperature outside. Without air circulation, the air inside heats up quickly. This creates ideal conditions for plant growth.
Temperature control in a greenhouse
Thermal radiation quickly heats the air inside the greenhouse and slowly warms the soil. Warm air, in turn, contributes to the receipt and, most importantly, the preservation of heat by the soil. Due to its organic properties, the soil is able to retain heat for a very long time, even when the source of thermal radiation becomes inactive, for example, in a simple greenhouse without heating, the soil heated during the day by the sun retains the heat received during the night.
But if the greenhouse were only to heat up endlessly, the temperature inside would soon become unsuitable for plants, right? The fact is that the greenhouse device contributes to fully automatic thermoregulation.
According to the laws of physics, the soil heats up during the day due to the fact that the air temperature in the greenhouse is high during the day, and at night, when the air temperature drops without sunlight, the soil, on the contrary, begins to give off the stored heat, heating the air . Such a simple cycle creates a constant temperature regime inside the greenhouse.
More advanced greenhouses also use additional means of heating, which makes it possible to manually control thermoregulation without regard to the weather, but the basic principle of obtaining-saving-releasing heat remains the same.</p >
Protection from external influences
Another important purpose of the greenhouse is to protect your garden crops from the adverse effects of the external environment. In this regard, greenhouses perform the same function for plants as a house does for a person. Such protection is especially important in the autumn-winter season.
The greenhouse protects:
- From the wind, which brings dust and weed seeds, blows off seedlings, and a strong wind can damage the plant and even uproot it. Sturdy greenhouses with a strong hull are the only way out for windy regions (a well-made greenhouse can withstand even a small storm).
- From precipitation. For example, by protecting plants from rain, you yourself control how much water they will receive.
- From most pests. You will not need to treat plants with chemicals that are harmful to both plants and you. Of course, it is impossible to make sure that not a single bug gets into the greenhouse, if only because some harmful insects can move underground, but the greenhouse is quite capable of significantly reducing the “presence” of pests on your vegetables.