Would a liquid's refractive index measured at a high altitude be different from that measured at sea level?

By definition, refractive index is the ratio of the velocity of light in vacuum to the velocity of light in a specified medium. The medium here is the liquid. The speed of light through the liquid also depends on the temperature and pressure. At sea level, the liquid is higher in temperature and pressure. So, the speed is gonna be relatively slower because of the movement of atoms. At high altitude, the liquid is at a lower temperature and pressure. The movements of the molecules are lesser, thus, light can move much faster. So, yes, it would be different. The refractive index would be closer to 1 at high altitude, and greater than 1 at sea level.