Suggest a method to liquefy atmospheric gases.

Liquifying atmospheric gases means to converting gaseous particles to liquid particles.

This involves reduction of the space between molecules, which can be done either by increasing the pressure on the gaseous particles present in any container or by decreasing the temperature of the gaseous particles, thereby decreasing the kinetic energy as a result of which forces of attraction between gaseous particle increases and particles come closer in the container and converts into liquid.