Air traffic delays and weather

You surely have heard about the flights gets delayed because of the non suitable weather conditions.
The typical conditions that cause delay is low visibility, low cloud ceilings, thunderstorms, icing conditions and high winds.
Basically, there are two sets of flight regulations that relate to flying in weather VFR (visual flight rules) it regulates the flights in good weather.
And the other is IFR (Instrument Flight Rules) it permits the fly from the clouds, but the aircraft surely passed through its path and follow the instructions for departure and approach.
If the aircraft is at 18000 feet above, it has to be on IFR flight plans  because of the weather. 

All the major airport users IFR all the time. Runways are never close due to weather, but the conditions of instruments may not permit an aircraft to depart or arrive at the airport. 
Rain also affects the conditions, rain reduces the visibility and it causes problems on braking ability on landing. And now you must be thinking about the winds? Well, there is no maximum crosswind rating for airplane. There is so much to learn about the weather conditions and the delays on departures and take off, but yes, these are the things which are most cared and noticed. They should be!