Tachypnea - Distinction from other breathing terms. 1  Different sources produce different classifications for breathing terms. 2  Some describe tachypnea as any rapid breathing. Hyperventilation is then described as increased ventilation of the alveoli (which can occur through increased rate or depth of breathing, or both) where there is a smaller rise in metabolic carbon dioxide relative to this increase in ventilation.
However, guidance is also possible, e.g., by the use of reflections, e.g. at metallic interfaces. Some waveguides also involve plasmonic effects at metals. Figure 1: Two different kinds of waveguides. Planar waveguides guide light only in the vertical direction, whereas channel waveguides guide in two dimensions.
Scientists use a form of visible radar called lidar (light detection and ranging) to measure air pollution with lasers. Archeologists and geologists point radar down into the ground to study the composition of the Earth and find buried deposits of historical interest. One place radar isn't used is on board submarines. Electromagnetic waves don't travel readily through dense seawater (that's why it's dark in the deep ocean). Instead, submarines use a very similar system called SONAR (Sound Navigation And Ranging), which uses sound to see objects instead of radio waves.