C9 : The atmosphere today and Greenhouse gases

Question 1

How much nitrogen and oxygen are in the atmosphere today

Answer 1

80% nitrogen
20% oxygen
as well as small amounts of other gases like CO2, water vapor and noble gases such as Argon

Question 2

Why does the atmosphere act as a layer of insulation keeping Earth warm

Answer 2

Because of greenhouse gases. This is because :
. Electromagnetic radiation from the sun radiates to Earth
. 30% is reflected back to space by the atmosphere
. The remaining radiation warms up the Earth
. Some of the radiation that is ‘short wave’ radiation like UV which passes through the atmosphere is radiated back to space as ‘long wave’ infrared radiation
. This radiation is absorbed by greenhouse gases increasing the temperature of the Earth

Question 3

What are some ways humans add greenhouse gases to the atmosphere

Answer 3

. Burning fossil fuels releasing CO2
. Deforestation resulting in fewer trees to take in CO2 through photosynthesis
. Rice fields releasing methane
. Grazing cattle releasing methane