What are three global processes that are caused by convection?

We know, that Convection is the movement of groups of molecules within fluids such as liquids or gases, and within rheids

Examples of Global processes occurs by it:

1) Atmospheric Circulation. - It is the large-scale movement of air, and is a means by which thermal energy is distributed on the surface of the Earth, together with the much slower (lagged) ocean circulation system.

2) Oceanic Circulation . - Solar radiation affects the oceans: warm water from the Equator tends to circulate toward the poles, while cold polar water heads towards the Equator. 

3) Weather. - Most important process if Weather including mineral cycle. Example in Hydrological cycle a foehn wind is a down-slope wind which occurs on the downwind side of a mountain range. It results from the adiabatic warming of air which has dropped most of its moisture on windward slopes.

Hope this helps!

It will appear as o2(g) as a reactant