A special type of glass is used in greenhouses as a medium for selectively transmitting spectral frequencies. The word "spectral" is derived from the adjective "spectral." Some of the topics covered in this book:
how the greenhouse capture the sunlight and use it
types of greenhouse
how to grow vegetables in a greenhouse
management of toxic emissions
Greenhouse desing, and many more as you navigate through the book
For the sake of clarity, let's define spectral frequency in terms of the following: every object in the universe radiates, emits, or transmits light. The material composition of an object dictates the wavelengths of light it emits and their distribution across an electromagnetic spectrum. As a result, the greenhouse's glass traps energy, which is then used to heat the plants and the ground inside. Because of this, it prevents air from rising and escaping its confinement. For example, small windows near the greenhouse's roof can significantly lower the temperature. This is because of the automatic cooling system's auto vent feature. Basically, greenhouses use an autovent to keep the temperature stable inside. When electromagnetic radiation is trapped in a structure in this way, no convection occurs (transfer of heat by currents within a fluid). It dates back to Roman times, when the Romans were the first to construct a structure to safeguard plants, as documented in historical records. In order to create primitive greenhouses, they used heated pits to build up rock slabs. During the 17th and 18th centuries, the correct name for this structure was "glasshouse." For plants to thrive at that time, it was incorrect to think they needed more heat than light. When the glass tax was repealed in 1845, greenhouse design began to shift away from obstructing the passage of light. They discovered that a greenhouse could be strengthened structurally while also absorbing more light if it had a curved roof rather than a flat one. They also discovered that using iron rather than wood allowed for higher concentrations of solar rays.
