Pathways of Energy Entering the Atmosphere
- When solar radiation (insolation) enters the Earth’s atmosphere, some of the energy becomes unavailable for ecosystems due to being:
- Absorbed by inorganic matter
- Reflected back into the atmosphere
- This means very little of the sunlight available from the Sun is converted into biomass in ecosystems
- About 51% of the available energy from the Sun never reaches producers
- The pathway of radiation through the atmosphere involves a loss of radiation through reflection and absorption, with the following (approximate) percentage losses:
- Reflection from clouds ~ 19%
- Absorption of energy by clouds ~ 3%
- Reflection by scatter from aerosols and atmospheric particles ~ 3%
- Absorption by molecules and dust in the atmosphere ~ 17%
- Reflection from the surface of the Earth ~ 9%
- The ability of clouds and reflective surfaces on Earth (such as snow and ice) to reflect solar radiation is known as albedo
- Of the 49% of solar radiation absorbed by the ground, only a small proportion ends up in producers
- Most incoming solar radiation fails to enter chloroplasts in leaves because it is reflected, transmitted (passes straight through the leaf), or is the wrong wavelength to be absorbed
- Of the radiation captured by leaves, only a small percentage ends up as biomass in growth compounds because the conversion of light to chemical energy is inefficient
- In total, only around 0.06% of all solar radiation falling on Earth is captured by plants
From the sun to producers - the pathway of solar energy entering the atmosphere
