hemsul=ParametricPlot3D[{2 Cos[λ]Cos[ϕ],2Cos[λ]Sin[ϕ],2Sin[λ]},{ϕ,-π,π},{λ,-π/2,0},Boxed->False,PlotStyle->{LightGray}]

hemnorte=ParametricPlot3D[{2 Cos[λ]Cos[ϕ],2Cos[λ]Sin[ϕ],2Sin[λ]},{ϕ,π/2,3π/2},{λ,0,π/2},PlotStyle->{LightGray}]

Show[hemsul,hemnorte]

ParametricPlot3D[{1+Cos[θ],Sin[θ],0},{θ,0,2π}]

ParametricPlot3D[{1+Cos[θ],Sin[θ],(((4-(((1+Cos[θ]))^2)-(((Sin[θ]))^2)))^(1/2))},{θ,0,2π}]

ParametricPlot3D[{1+Cos[θ],Sin[θ],-(((4-(((1+Cos[θ]))^2)-(((Sin[θ]))^2)))^(1/2))},{θ,0,2π}]

cilindro=ParametricPlot3D[{1+Cos[θ],Sin[θ],t(((4-(((1+Cos[θ]))^2)-(((Sin[θ]))^2)))^(1/2))},{θ,0,2π},{t,-1,1},PlotStyle->{LightGray}]

Show[hemsul,hemnorte,cilindro]