Where the cold downdraft reaches the surface, the air spreads out ...

[Brittanyd9008]

Where the cold downdraft reaches the surface, the air spreads out horizontally in all directions. The surface boundary that separates the advancing cooler air from the surrounding warmer air is called a ___________________ _.
  Fill in the blank with correct word.

Question 2

  Scattered thunderstorms (sometimes called pop-up or popcorn storms) that typically form on warm, humid days are often referred to as ___________________ _ thunderstorms or ___________________ _ thunderstorms.
  Fill in the blank with correct word.
 

[Chocorrol77]

Answer to Question 1

ANSWER: gust front

Answer to Question 2

ANSWER: ordinary cell; air-mass
air-mass; ordinary cell
ordinary; air mass
air mass; ordinary