Compared to today, the earth before the deluge was a much different place to live. For example, evidence points to the fact that, before the deluge, the earth had a year consisting of 360 days as opposed to today's year which consists of a fraction more than 365 days. A comparison of several verses in Genesis (Genesis 7:24, 7:11, and 8:4) shows that five months consisted of 150 days. This would mean that the pre-flood days were slightly longer than the present 24 hour days.
The earth before the flood was a lush tropical forest with large amounts of vegetation. Since the days were longer the temperature was warmer. After the waters receded the ice ages began and the earth's ecosystem changed. Before God brought the waters there would have been less wind and atmospheric turbulence. Winds are caused by temperature differences cause by the tilt of the earth's axis, mountain systems and ice caps. All of these cause unequal regions of hot and cold on the globe which produce the various winds. The pre-flood earth was warmer, had more vegetation, had smaller oceans, and had smaller mountains compared to today.
The atmosphere of the earth, before the flood, had less particles for rain to condense around than what we find today. Particles called condensation nuclei are absolutely essential to the formation of rain drops.
"Some atmospheric particles . . . formed by the evaporation of water from droplets of sea spray, are natural and even beneficial atmospheric constituents. Very small particles called condensation nuclei serve as bodies for atmospheric water vapor to condense upon . . . " (Manahan, Stanley E. Environmental Chemistry (7th ed). Lewis Publishers/CRC Press. Washington DC. p. 267. 2000)
If the earth before the flood had smaller oceans, then the production of particles for water drops to condense around would be very small if not non-existent. Less atmospheric turbulence would also have led to few particles put into the air. After the waters receded, the change in weather patterns, the formation of condensation nuclei from oceans, increased volcanic activity and the increased wind systems would have produced rain.
The lack of rain, however, did not mean the pre-flood earth was dry. Since the earth would have been warmer and laden with moisture that was not condensed, there would have been an extremely efficient condensation cycle. Condensed water droplets would have been bigger and more commonplace. The earth's surface would have cooled very rapidly at night. This drop in temperature would have caused a very large condensation cycle. This would mean the planet would have been watered, not by water drops falling from the sky, but by a very heavy mist or fog each day (possibly at sunset and sunrise).