Waves always refract toward regions of slower wave speed

Evidence

If you are sitting inside the lower medium, the wave crests arrive one after the other with the same period as in the medium above. (If a person above the surface of a pool is waving her arm once per second, the period will be one second whether you are looking from above or below the surface.) Because the wave is moving more slowly in the lower (blue) medium, the wavelength must be shorter to keep the frequency f the same. The rule is f = c1/λ1 = c2/λ2, where the c’s are the wave speeds and the λ’s are the wavelengths in the two media. — Eric J. Heller, Why You Hear What You Hear- An…, 181 (#expands, via linked claim)

Categorization

• XREF: connects to: Waves in random media always focus into hot spots without any lens; Wind gradients refract sound toward slow regions and extend its range; Frequency stays constant across media, so slow speed shortens wavelength — Eric J. Heller, Why You Hear What You Hear- An…, 181 (+1 more)

Related

• Frequency stays constant across media, so slow speed shortens wavelength (similarity 0.91)
• Sound refracts toward slower-speed regions over long outdoor distances (similarity 0.85)
• Wind gradients refract sound toward slow regions and extend its range (similarity 0.85)
• Wind speed gradients, not wind itself, refract sound and break reciprocity (similarity 0.85)
• A moving medium shifts sound speed, and speed gradients bend waves by refraction (similarity 0.83)
• Refraction bends waves toward the medium with slower speed (similarity 0.83)
• The frequency-wavelength-speed relation governs waves in every medium. (similarity 0.82)
• More diffraction occurs for longer-wavelength, lower-frequency sound (similarity 0.82)
• Sound bends like light because temperature changes its speed. (similarity 0.81)
• Wind bends sound waves because air velocity changes with height (similarity 0.81)
• Prevailing wind direction should guide where one lives relative to noise sources (similarity 0.80)
• Lower frequencies diffract more around obstacles than higher frequencies do (similarity 0.80)
• Fast wave propagation does not require fast motion of the medium itself. (similarity 0.80)
• Downwind sound is bent downward and waveguides along the ground, gaining intensity (similarity 0.80)
• Atmospheric physics creates striking asymmetries in how sound travels (similarity 0.80)

Broader Connections

• Wind gradients refract sound toward slow regions and extend its range #exemplifies (0.95)
• Wind speed gradients, not wind itself, refract sound and break reciprocity #exemplifies (0.95)
• Frequency stays constant across media, so slow speed shortens wavelength #expands (0.90) — Eric J. Heller, Why You Hear What You Hear- An…, 181