Observing & Predicting

Flash floods scoured Phoenix and surrounding areas on September 8, 2014. How did the rainfall totals compare to normal September precipitation?

Tuesday, September 1, 2009

  •  The Sun is the main source of power for the Earth's climate machine. Space-based measurements, begun in 1978, indicate Earth receives an average of 1,361 W/m<sup>2</sup> of incoming sunlight, and the amount varies by about one-tenth of a percent over the course of the 11-year solar cycle.