A green light usually last a minute to two minutes.
Stale green light is a term used in traffic terminology. Essentially, it means that the green light has been green so long that it's about to turn yellow.
It takes 2-3 minutes for a traffic light to change from green to red! (P.S I have counted the seconds myself!)
If you are blocking traffic flow for a long time then yes.
The green light on the traffic light is on the bottom. The yellow is in middle, the red is on top. However, in some municipalities, the traffic lights are not vertical, they are horizontal. In these instances, the green light is usually, but not always, the furthest to the right.
A traffic light you seen change to green
a fresh green light is when the traffic light has just turned from red to green
When the traffic light comes into view and it's green, it was likely green for a long time, unless you also observe cars just starting to get going. If you see the traffic light is green in the distance we call this green light "stale", meaning it could turn yellow any second. A traffic light that just turned green, we call this green light "fresh", meaning it just turned green and it won't be turning yellow for a little while. Of course these times between from when it turns green then back to yellow and red again varies on the intersection. To answer the question when you're approaching a green traffic light you should prepare to stop as that green light is "stale". You don't necessarily have to slow down just get ready to hit the brake.
It is usually on the bottom of the traffic light.
The lowest light on a traffic signal is green. Some cities use traffic lights that are not arranges top to bottom but rather side to side. In this event the green light is usually the furthest to the right.
'Go'.
Yellow light
On a vertical display traffic signal the green light is on the bottom. On a horizontal display traffic signal it is to the right, but may depend on that state (or municipality's) practice.