Extinction Law at a Distance up to 25 kpc toward the Galactic Poles
  Photometry from the Tycho-2, 2MASS, and WISE catalogues for clump and branch
giants at a distance up to 25 kpc toward the Galactic poles has allowed the
variations of various characteristics of the infrared interstellar extinction
law with distance to be analyzed. The results obtained by the extinction law
extrapolation method are consistent for different classes of stars and
different characteristics as well as with previous studies. The conventional
extinction law with a low infrared extinction is characteristic of only a thin
layer no farther than 100 pc from the Galactic plane and of two thin layers
near $Z=-600$ and $+500$ pc. Far from the Galactic plane, in the Galactic halo,
the infrared extinction law is different: the extinction in the $Ks$, $W1$,
$W2$, $W3$, and $W4$ bands is, respectively, $0.17$, $0.16$, $0.16$, $0.07$,
and $0.03$ of the extinction in the $V$ band. The accuracy of these
coefficients is $0.03$. If the extinction law reflects primarily the grain size
distribution, then the fraction of large dust grains far from the Galactic
plane is greater than that in the circumsolar interstellar medium.
