OK our particles will be cubes so...add one !!

Size it as shown and importantly add some segments to the z axis, 10 may be overkill but as we are going to be bulging this cube we need some amount of segments, the more you add the smoother the bend will be

Move the cube well out of the image, behind the emitter, depending on where your sphere is, I had this one at - 2500 m

OK click on the PStorm node and in object manager change the details as shown

Now PStorm will by default emit for the duration of the animation, there are a few ways to control this ( see the TP tutorial manual for one)

You can of course key frame the emitter but I will show you a technique I used, if this is not available in earlier versions of C4D then by all means keyframe

First add an On port to the input

Now add a particle birth port to the output

Now we need a PGroup for our particles, connect the particle birth port of the Pstorm to the input of the Pgroup. At the top of Xpresso choose custom- thinking partcle settings. from the window that opens drag the All group into your PGroup box we just created (sorry forgot to snag these images !!)

And a PPass node to control them and drop the All grou[ in to this box. ( may well work without this as we only have this 1 default group)

Create a PSize node and connect the PPass out put port to the input of the Psize, we are going to control the size by age

In attribute manager tick the over age box and set up a gradient similar to this one

Right click and add a time expression

To the left of the xpresso editor look in your Xpool, system presets for an Action timer and drag this into the editor

In the object manager set it to start at frame 0 and stop at frame 150