In this video I will explain how water vapor, H2O, in Earth's atmosphere also keeps Earth comfortably warm. Carbon dioxide is a linear molecule so it doesn't have a dipole moment. However water vapor molecule is “bent”, so it has a strong dipole moment, therefor the bent structure enable the water vapor molecule can have more than the 3 symmetric, bend, and antisymmetical vibrational mode. The other 3 vibrational modes that is characteristic of water vapor is the rocking, twisting, and another rocking vibrational mode.