I'll try in helping you visualise gravity. :)
First, the basics. Gravity is a weak force, but has a long range. An electron, being such a small particle, still can exert its gravitational influence (albeit very weak) to the very end of the observable universe (if we had a sensitive enough instrument to measure it, we can!).
Now to the visualizing part. I assume you ask this question from the perspective of an observer on earth. From this perspective, "gravity" "reduces in its intensity" as we go skywards. Since you talk about "fluids", I'll try to help you visualise this on the basis that, the stronger the gravity is, the "darker" it is to see around. If you had the sense to visualize gravity in this sense, what you would see would be similar to what a fish would see in a murky pond. the deeper you are, the murkier and darker it gets. So on the surface of the earth, you wouldn't be able to see a thing, but, as you go higher, things start clearing up and when you reach "space", you start seeing things. In this case, the level of "darkness" corresponds to the strength of gravity.
What it means actually is that, from the perspective of a person on the surface of the earth, gravity reduces gradually from the surface as you move skywards.