1.   He and his students investigated these effects by measuring X-ray spectrums in many solids.

2.   Instruments measured the spectrum of water and ice particles in the clouds, air pressure, temperature and electric fields.

3.   The clouds were detected by measuring the spectra of light arriving at the Hubble from distant, very bright stars.

4.   The sensor, manufactured by Hamilton Sundstrand Sensor Systems in Pomona, California, shoots a laser through a substance and measures the spectrum on the other end.