Is it true that in tropical climates, rain fall occurs more in the
afternoons than in the mornings?

Hi oaikin:

Thanks for the interesting question. 

Yes, it is true that in the tropics, rain occurs more often in the
early afternoon than in the morning. However, one proviso to that is
that this only holds true for continental areas of the tropics - over
the tropical oceans, rain tends to fall overnight and into early
morning.

TRMM Application on Tropical Rainfall Diurnal Cycle
URL: http://daac.gsfc.nasa.gov/precipitation/trmm_apps/trmm_diurnal.shtml
Quote: "Diurnal cycle of precipitation over the global tropics derived
from the TRMM Combined Instrument algorithm (2B31). The pixel data are
binned into geographic local time 3 hourly 1x1 degree boxes. There is
a nocturnal to early morning maximum over the oceanic rain belts.
Rainfall maximum over the continents occurs in early afternoon. The
drastic shift of the maximum rainfall over the Maritime Continent from
early morning in the coast to late afternoon in land suggests a strong
coupling in land-air-sea interactions."
Note: Have a look at the interesting plots!

Tropical Rain Forest Climate 
URL: http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/climate_systems/tropical_rainforest_1.html
Quote: "A distinctive diurnal pattern of cumulus cloud development in
the morning, precipitation in the early afternoon, followed by
dissipating clouds towards the late afternoon is typical."

Search Strategy (on Google):
* tropical rain afternoon morning
* tropical rain afternoon morning diurnal

I hope this helps!

websearcher