The Earth's fluids -- principally in its oceans and its atmosphere - are constantly moving in a manner that serves to redistribute the incoming radiant energy from the sun in the warm tropics toward the Earth's cooler poles. Visible light is transformed into heat, and this heat is absorbed and conducted both in the oceans and in the atmosphere according to their respective thermodynamic characteristics. Changes in concentrations of particular gases in the atmosphere and salinity in the oceans can have a significant impact on the patterns of circulation of these respective fluids both in themselves and in relation to each other. An increase absorbtion of heat energy in the low latitudes can generate wide ranging global changes in the frequency, duration and relative force of storms emanating from the tropics.

Consider how hurricanes are formed and function to redistribute energy in the Earth's system. Note in particular how the hydrological cycle -- with its processes of evaporation and condensation -- are animated as a function of the heat exchange between the oceans and the atmosphere.

Repeated storm formation occurs over the late summer season in the northern hemisphere, and this period is often referred to as the hurricane season for that reason. Note below the dymanics of the 2005 season -- the longest and most intense on record. Scientists have understood the broad dynamics of tropical storm generation and movement for some time. They have been observing them for quite some time from space.

In light of all of this knowledge, can we say that hurricane Katrina came as a surprise?
Did we not know it could happen? or did we not believe it would happen? Why not?
What good did "Hurricane Pam" do for New Orleans?