Question: Is water vapor a gas, or a type of liquid?

The reason for this is related to the possibility that global warming could be more related to water than to carbon dioxide. Carbon dioxide is a gas, but what if water vapor is not?

A gas is a phase of matter, that includes solids and liquids. In order to get to a gas, there must be a phase change, and this is often related to temperature. Consequently, ice melts, and thus changes phase from a solid to a liquid. Likewise, water boils, and changes phase from liquid to a gas when it becomes steam. But if steam is a gas, is water vapor a gas? Water vapor occurs at a low temperature. Could it still be in a liquid phase, then?

Actually, it is considered a gas.

A bit of a segue here. The link points to another link about Kinetic theory of gases. It shows that the temperature of the ideal gas is proportional to the average kinetic energy of its particles. Gases are always in motion, then. All matter is in motion, but what makes gases different?

What makes a gas a gas, a liquid a liquid, and a solid a solid?

That question relates to the energy issue behind AGW. Energy relates to thermodynamics, and to entropy. Recall that entropy is the tendency of energy to spread out.

Something has to prevent entropy from spreading out the energy so that temperatures can go up. What is it about gases that make this impossible? ( my hunch, by the way) Gases do not have the limatations to its motion that liquids and solids have. It the motion that involves kinetic energy. Kinetic energy is simply matter in motion.

By the way, there is a lot more water in terms of mass, than there is matter in the atmosphere. This could explain periods of warmth or coldness, such as in ice ages.