Petrochelidon
![](/Images/godic/202501/05/Cliff_Swallow_Builder2836.jpg")
Petrochelidon is a genus of birds known as cliff-nesting swallows. The genus includes all of the five species of birds commonly called cliff swallow, and contains the following species:
Cliff Swallow
英语百科
- Doppler
- doppler sample volume
- Doppler satellite fixing
- Doppler satellite observation
- doppler search
- Doppler shift
- Doppler shift attenuation method
- Doppler shifted constant frequency
- Doppler shift effect
- doppler shift frequency spectra
- Doppler shift in frequency
- Doppler shift measurement
- doppler shift method
- doppler sidelobe
- Doppler signal
- doppler signature
- Doppler sodar
- Doppler sonagraph
- Doppler sonar
- doppler sonar current indicator
- Doppler sonar navigator
- Doppler sonar system
- Doppler sonar transducer
- Doppler sonography
- Doppler Sonography,Transcranial