Rays of Light - How they can be harenessed by Greenhouses

Every day, the sun beams down huge amounts of warmth and light onto the Earth, in the form of light waves, or ‘rays’. However, most of these rays are wasted, as we still have few effective ways of harnessing and storing them.
Greenhouses store these rays by using a very simple piece of science to their advantage. Basically, if you make a structure out of glass, then the sun’s rays can pass through the glass to get into the structure, but then get trapped inside.
This happens because of the unique structure of glass that allows light to pass through but not air. When the sun’s rays get into the greenhouse, they heat up the air, soil, rocks, plants and other things inside the greenhouse, which then retain the heat. As the heat that has been absorbed into the air and objects cannot simply escape again, the greenhouse gradually gets hotter and hotter because of the amount of heat that is being trapped inside.
One hot day can keep the inside of a greenhouse warm for several days, and even a normal day will be good enough to keep the greenhouse warm overnight.
By using the heat that is stored in the greenhouse, the plants inside can grow and make food for themselves, even when it’s cold outside. As the temperatures in greenhouses will rise far above the outside temperature in warm conditions, they allow you to grow plants that would usually only grow in a more tropical climate than there is where you live, such as exotic fruits and flowers.
However, because of the way greenhouses work, you need to be careful about how often you go in your greenhouse. Every time you open the door, a huge amount of the heat will escape, and if you’re going in there every day then the greenhouse will be next to useless. However tempting it might be to go in and look at your plants, they will do much better if you plant them and then leave them alone (look through the windows if you have to!), only going in very occasionally to water them.