What is "workspace attempt to call a table value?"

I made this script to simulate a lightning effect, The atmosphere color would turn white for around 2 seconds at random every 8 seconds, but i keep getting the error "Script:9: attempt to call a table value

My original script

Loop = true
while Loop == true do
wait (8)
local RandomNumber = math.random (1,2)
print (RandomNumber)
if RandomNumber == 2 then 
    Lightning = true
    if Lightning == true then
            game.Lighting.Atmosphere.Color = Color3(255,255,255)
            wait (2)
            game.Lighting.Atmosphere.Color = Color3(88, 98, 122)
    Lightning = false   
    end
end
end

Ive Tried ,

    game.Lighting.Atmosphere.Color = Enum.Color3.new(1,1,1)
            wait (2)
    game.Lighting.Atmosphere.Color = Enum.Color3.new(0.345098, 0.384314, 0.478431)