# Does water really have strong EM absorption at 3 kHz in solid and 2 GHz in liquid? Why the huge shift?

While writing this answer to the question Transmitter receiver coil separation for Electromagnetic Terrain Conductivity Measurement I ran across this large PDF file of a book Soil and Environmental Analysis; Physical Methods Soil and Environmental Analysis; Physical Methods, 2nd Ed. K. A. Smith and C. E. Mulllins, Eds. 2000 Dekker, New York.

Figure 5. on page 29 is shown below. It shows a plot of the real and imaginary part of the permittivity of water in solid (ice) and liquid forms.

The shapes are the roughly the same; the real part is around 80 to 90 at low frequency and drops to perhaps 2 to 1 at high frequency, with the imaginary part reaching a peak as the slope of the real part is maximum as one would expect.

The difference however is that the peak in the absorption is around 3 kHz for ice and 20 GHz for liquid!

1. Is the physics behind this strong absorption peak the same in both cases?
2. If so, what is it about the transition from solid to liquid that can move it seven orders of magnitude?

• Wow, great question! Maybe this paper will shed some light: J.H. Jiang, D.L. Wu, Ice and water permittivities for millmeter and sub-millimeter remote sensing applications, Atmos. Sci. Let., 5 (2004) 146-151. The authors are/were at JPL at CalTech. The paper is not paywalled. I hope to read (and understand) a good answer here!
– Ed V
Commented Jul 13, 2019 at 22:53
• @EdV Wow that looks quite helpful for the GHz line at least (radar doesn't usually go down to kHz); I'll give it a read, thanks! It's open access here and also posted at JPL here
– uhoh
Commented Jul 13, 2019 at 23:06
• Please note: This is a relaxation spectrum. The transitions do not come from a resonance (absorption, like in NMR, IR, etc.), but an applied electric field has a lossy (at low frequencies) or elastic (at higher f.) effect on some mode of molecular orientation of electrical dipoles in your sample.
– Karl
Commented Jul 14, 2019 at 8:51
• en.wikipedia.org/wiki/Dielectric_spectroscopy
– Karl
Commented Jul 14, 2019 at 8:57
• Intuitively I know the answer, bit it is not authoritative. Commented Apr 14, 2022 at 5:44