Visit the website given below and study the effect of the concentration of greenhouse gas on greenhouse-effect

Question

Accepted Answer

Note on the printed page: in the English edition (page 258) the web address itself is missing — a blank white box is printed where the link should be, and only the last part of the address, "greenhouse-effect", survives. The same question in the Hindi edition Anveshan (page 258) prints the full address, so use that: https://phet.colorado.edu/en/simulations/greenhouse-effect — the PhET "Greenhouse Effect" simulation. What to do in the simulation, and what you will see: What you change What happens on the screen The physics behind it Set the greenhouse gas concentration to none Almost every infrared photon leaves; the surface temperature falls sharply Nothing intercepts the outgoing IR, so the Earth loses heat as fast as it gains it — at a low temperature Set it to ice age or 1750 levels Some IR photons bounce back; temperature settles at a moderate value A modest greenhouse effect — the one that made life possible Slide it up to today and beyond More IR photons are absorbed and re-emitted downwards; the thermometer climbs More absorbers means a longer delay before heat escapes, so a higher steady temperature Watch the photons view Yellow (sunlight) passes down freely; red (infrared) is caught by CO 2 and CH 4 molecules Greenhouse gases are transparent to visible light but opaque to infrared — the heart of the effect The conclusion you should write down: raising the concentration of greenhouse gas does not change how much sunlight comes in. It changes how easily heat gets out .

What you change	What happens on the screen	The physics behind it
Set the greenhouse gas concentration to none	Almost every infrared photon leaves; the surface temperature falls sharply	Nothing intercepts the outgoing IR, so the Earth loses heat as fast as it gains it — at a low temperature
Set it to ice age or 1750 levels	Some IR photons bounce back; temperature settles at a moderate value	A modest greenhouse effect — the one that made life possible
Slide it up to today and beyond	More IR photons are absorbed and re-emitted downwards; the thermometer climbs	More absorbers means a longer delay before heat escapes, so a higher steady temperature
Watch the photons view	Yellow (sunlight) passes down freely; red (infrared) is caught by CO₂ and CH₄ molecules	Greenhouse gases are transparent to visible light but opaque to infrared — the heart of the effect

NCERT Solutions for Class 9th Science Chapter 13 .1.3 Role of the atmosphere — Pause and Ponder