Why are levels of carbon dioxide high at night and low at noon?

Answer 1

Although CO2 changes very, very slightly on a daily basis, this difference can most likely be accounted for by plants' failure to undergo photosynthesis during night. This means that less carbon fixation occurs, and more is left in the air than during the day time when it is used to make carbohydrates. At the same time, autotrophic organisms such as humans take in oxygen and release more CO2 into the air, so CO2 levels are most likely highest at sunrise.

Answer 2

The opposite is true. At night time, the plants have a limiting factor in the form of light (there is very little indeed). Photosynthesis therefore ceases, and the carbon dioxide in the atmosphere stops being taken in by plants and used up. Respiration (a process carried out by all organisms and one that produces carbon dioxide as a by-product) continues however. The carbon dioxide levels therefore rise :) x

Answer 3

Carbon dioxide levels are lower in the daytime because the sunlight means that plants have energy to photosynthesise, absorbing carbon dioxide through the stomata and therefore lowering the carbon dioxide level.

Answer 4

At night, plants stop photosynthesis and release carbon dioxide through respiration, contributing to higher levels. During the day, photosynthesis by plants absorbs carbon dioxide from the atmosphere, reducing levels. Additionally, human activities like burning fossil fuels can also contribute to higher carbon dioxide levels at night.

Answer 5

Because the sources to release CO2 increases during day time viz. animals, factories, vehicles etc.