The first is temperature. That is simply how hot or cold the air is. During the day, the atmosphere is warmed by the sun, so the temperature goes up. At night, after the sun goes down, the atmosphere cools and the temperature drops. Another property is called pressure.
Pressure is how thick or dense the air is.
The atmosphere is several kilometers thick. That means there is a lot of air above us, and it's all pushing down on top of us. On the surface, pressure is usually pretty constant from one place to another. But, often there are small differences, and these differences are what lead to all the weather we experience. When two neighboring regions are at different pressures, they are out of balance with each other.