The magnitude of the average electric field normally present in the atompshere just above the surface of the Earth is about 150 N/C, directed inward towards the centre of the Earth. This gives the total net surface charge carried by the Earth to be:
$\text{ (Given }{\mathrm{\epsilon }}_0=8.85\times {10}^{-12}{\mathrm{C}}^2/\mathrm{N}-{\mathrm{m}}^2,\mathrm{R}=6.37\times {10}^6\mathrm{m}\text{ ) }$