Greenhouse Effect


[G.H. Effect]





The Greenhouse Effect: Image from Austrailian Greenhouse Office

Q: Describe the Greenhouse Effect

A: The "greenhouse effect" was discovered several centuries ago when translucent materials were first starting to be used. Light passes through materials like glass or plastic (or gases like carbon dioxide in the atmosphere), hit an opaque surface, and is partially transformed to heat. The darker the surface, the less reflective of light, and, hence, the higher the heat generated. These "light" transparent materials like glass or plastic are "opaque" to heat which means they reflect much of it back into the greenhouse. This "trapped" heat will slowly conduct (not radiate ) through the surface. The worse a material conducts heat the better insulating effect. Single pain glass is poor insulator so double pane glass or plastic is often used.

Image from Austrailian Greenhouse Office - Click here!In a passive solar greenhouse, the idea is to store this heat during the day and slowly release it at night. Water is one of the best heat storage mediums so you may see 55 gallon drums of water painted black inside a greenhouse. Rock, cinder block, and cement slabs are also used as "thermal mass" solar heat sinks.

The concern with greehouse gases in the atmosphere is that they're raising the earth's temperature. A few degrees can have dramatic impact on the climate. I'm wondering if these recent droughts in the Midwestern and Eastern US as well as the heavy rains in the West Coast are some early signs of climate change. It sure seems different from 30 years ago!
Images from Austrailian Greenhouse Office
What can we do as individuals?



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