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Geolens

Glossary

417 words used in the labs.

Find a term from the labs, understand the process behind it, and see how it appears in the landscape. Each entry connects an explanation with a real observation and a model you can explore.

Term

Solar constant

Also written: Total solar irradiance

Total solar irradiance near Earth's mean orbital distance, about 1,361 W m⁻² on a surface perpendicular to the rays above the atmosphere. It varies slightly over time.

What to look for

NASA SDO observes the solar photosphere and sunspots. The Sun supplies incoming solar radiation (insolation). The solar constant is irradiance near 1 AU on a plane perpendicular to the rays, about 1,361 W m⁻²; it is not measured by this visible-light photograph.

Related labs

Sun and Earth →
An SDO observation of the solar photosphere showing a large dark sunspot group.
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Explore further with USGS water glossary · USGS volcano glossary · NPS glacial geology · NASA Earth facts. Photograph acknowledgements are collected on the Image credits page.