Known for hot temperatures, Southern California and the rest of the Southwest United States are undergoing a cold snap that has set records in many areas throughout the region.
Periodogram is the spectrum of a set of time signal usually obtained by fast Fourier transform (FFT). It usually shows frequency as x-axis, and magnit... This page may be out of date.
A sonogram is the image generated during ultrasonography, which is a diagnostic imaging technique that uses ultrasound to visualize anything inside the body. Ultrasound is sound with a frequency above the range audible to humans, about 20 kHz.