I've been monitoring the Android market "News & Weather" category since we published our "Radar Now!" app and have noticed some interesting behavior in how the market moves apps to the top of the popularity tab. Most apps, like "Radar Now!" experience slow and steady growth, or none at all. Other apps zoom from nowhere to the front of the line. This graphic represents eight apps sampled over a little more than a month. The numbers on the left hand side indicate the app's overall placement in the market, the lower the better.
Click on the graphic for a full size image.