Climate change: average over a long time 30yrs or more. May be an increase, decrease, or new spatial pattern. Shifting the probability distribution of weather events. Climatology includes weather warmer and colder than normal. Decadal averages cannot always tell that the climate is changing. What affects air temperature: amount of sunlight received, altitude (cooler at higher elevations, the earth system. Wind speed is stronger over ocean than land because less friction. Deserts are an exception, have no obstacles, strong wind. Energy has to be added to make any of the reactions happen. All of these forms of energy are relevant to the climate system. The rate at which energy is used or received is called power. Watt: the unit of power (energy per time) Climate scientists refer to sunlight as solar radiation. Unless things are really hot, they gi(cid:448)e off light at (cid:449)a(cid:448)ele(cid:374)gths our eyes ca(cid:374)"t detect.