To apply lines on a sphere, you could use Interpolate between two paths (half circles). Like this for example:
(1). Draw a circle, then draw a vertical line, align them both using the Align tool. Select both the circle and the path, go to
Path > Cut path. This will use the path (which is on top) to cut the path of the circle into two separate paths.
(2). Select the right half of the circle, go to
Path > Reverse. This is an important step, and is NOT the same as simply flipping it.
(3). Select both halfs of the circle, go to
Extensions > Generate from path > Interpolate. In this case, I chose the following settings: exponent 0, interpolation steps 6, duplicate endpaths off, interpolate style on. Click Apply, or use Live preview before clicking apply.
Notice that the lines have equal distance to each other. On a real sphere this would not be the case because of perspective, but it might be good enough. To make it more realistic, you may want to do these extra steps:
(4). Copy one of the paths (here I chose the green one). Edit its nodes to make it closer to the outside circle (yellow is the result).
(5). Copy the resulting path, flip it, and move it to the other side. That's better!
Now, if you don't want to see the "poles" of the sphere, you could use a circle to clip it:
(6). Draw a circle, align it on top of the sphere (group the lines of the sphere beforehand), make it a little smaller than the sphere, and a bit transparent. Duplicate it, move one behind all the others (you will use it later).
(7). select the sphere and the transparent circle on top (2 objects), right click, then
Create clip (or go to
Object > Clip > Set). The back circle will appear. Change colors etc.