The component of total radiation (or solar energy) received at the Earth’s surface that directly enters the atmosphere.
The total radiation (or solar energy) received at the Earth’s surface consist of two components: (1) direct radiation and (2) diffuse radiation. Direct radiation refers to that solar radiation that has directly entered the atmosphere (as opposed to that which entered the atmosphere by reflecting from clouds, gases, aerosols etc.).
- Direct radiation is one of the UKCP09 Weather Generator variables, measured in watts per square metre (W/m2).
- An overview of the outputs from the UKCP09 Weather Generator is provided in Section 1.4 of the Climate change projections report.