Amass of cold, dry air is a mass of warm, humid air. consequently, warmer (lighter) air is often forced to rise above the sloping frontal surface overlying colder (denser) air.

A mass of cold, dry air is lighter than a mass of warm,humid air.
The lighter warm air slides up and over the cold air. wWarmer (lighter) air is often forced to rise above the sloping frontal surface overlying colder (denser) air. There is a boundary separating two masses of air of different densities.The air masses separated by a front usually differ in temperature and humidity.

  the answer is don't know.

I'm having some difficulty seeing the diagram clearly.but the question says there's a net inward force on the object.so we know right away,  from newton's 2nd law of motion, thatthat baby is accelerating.  it doesn't even matter which way thenet force is pointing.  if there's any net force, then either theobject's speed or else its direction must be changing.