The way I was taught is that ao (青) covers all shades of blue and green, although depending on context its meaning can be limited to blue. So for instance if b

The way I was taught is that ao (青) covers all shades of blue and green, although depending on context its meaning can be limited to blue. So for instance if both ao (青) and midori (緑) are used to designate sports teams, then the ao (青) team will be the blue team. Due to this ambiguity with the word ao (青) it's in general better to use a more precise word to specify the shade of blue/green, like koniro (紺色) for deep blue, mizuiro (水色) for light blue, midori (緑) for green, etc.