The answer is "a cold front."

A cold front moves faster than a warm air mass. The warm humid air is pushed up and results in a short period of heavy rain and possibly violent thunderstorms.

A warm front moves slower  than a cold air mass. The warm raises steadily above the cooler air mass and causes gentle rain showers for longer periods of time.

An occluded front is a combination of two fronts that form when a  cold front catches up and overtakes a warm front. The result is a mix of rain showers and thunderstorms.

A stationary front is the boundary between two air masses when neither is moving. Clear skies to partly cloudy skies may result, with occasional light rain.

The answer is "a warm front."

A cold front moves faster than a warm air mass. The warm humid air is pushed up and results in a short period of heavy rain and possibly violent thunderstorms.

A warm front moves slower  than a cold air mass. The warm raises steadily above the cooler air mass and causes gentle rain showers for longer periods of time.

An occluded front is a combination of two fronts that form when a  cold front catches up and overtakes a warm front. The result is a mix of rain showers and thunderstorms.

A stationary front is the boundary between two air masses when neither is moving. Clear skies to partly cloudy skies may result, with occasional light rain.

The answer is "gentle showers."

A cold front moves faster than a warm air mass. The warm humid air is pushed up and results in a short period of heavy rain and possibly violent thunderstorms.

A warm front moves slower  than a cold air mass. The warm raises steadily above the cooler air mass and causes gentle rain showers for longer periods of time.

An occluded front is a combination of two fronts that form when a  cold front catches up and overtakes a warm front. The result is a mix of rain showers and thunderstorms.

A stationary front is the boundary between two air masses when neither is moving. Clear skies to partly cloudy skies may result, with occasional light rain.

A cold front moves faster than a warm air mass. The warm humid air is pushed up and results in a short period of heavy rain and possibly violent thunderstorms.

A warm front moves slower  than a cold air mass. The warm raises steadily above the cooler air mass and causes gentle rain showers for longer periods of time.

An occluded front is a combination of two fronts that form when a  cold front catches up and overtakes a warm front. The result is a mix of rain showers and thunderstorms.

A stationary front is the boundary between two air masses when neither is moving. Clear skies to partly cloudy skies may result, with occasional light rain.

The answer is "a cold front."

A cold front moves faster than a warm air mass. The warm humid air is pushed up and results in a short period of heavy rain and possibly violent thunderstorms.

A warm front moves slower  than a cold air mass. The warm raises steadily above the cooler air mass and causes gentle rain showers for longer periods of time.

An occluded front is a combination of two fronts that form when a  cold front catches up and overtakes a warm front. The result is a mix of rain showers and thunderstorms.

A stationary front is the boundary between two air masses when neither is moving. Clear skies to partly cloudy skies may result, with occasional light rain.

The answer is "high winds" because the types of air masses were not defined and wind is caused by differences in air pressure.

A cold front moves faster than a warm air mass. The warm humid air is pushed up and results in a short period of heavy rain and possibly violent thunderstorms.

A warm front moves slower than a cold air mass. The warm air raises steadily above the cooler air mass and causes gentle rain showers for longer periods of time.

An occluded front is a combination of two fronts that form when a cold front catches up and overtakes a warm front. The result is a mix of rain showers and thunderstorms.

A stationary front is the boundary between two air masses when neither is moving. Clear skies to partly cloudy skies may result, with occasional light rain.

The answer is "The westerlies move air masses from west to east but sometimes get deflected by the jet stream."

A cold front moves faster than a warm air mass. The warm humid air is pushed up and results in a short period of heavy rain and possibly violent thunderstorms.

A warm front moves slower than a cold air mass. The warm air rises steadily above the cooler air mass and causes gentle rain showers for longer periods of time.

An occluded front is a combination of two fronts that form when a cold front catches up and overtakes a warm front. The result is a mix of rain showers and thunderstorms.

A stationary front is the boundary between two air masses when neither is moving. Clear skies to partly cloudy skies may result, with occasional light rain.

The answer is "The Jet Stream"

A cold front moves faster than a warm air mass. The warm humid air is pushed up and results in a short period of heavy rain and possibly violent thunderstorms.

A warm front moves slower than a cold air mass. The warm air rises steadily above the cooler air mass and causes gentle rain showers for longer periods of time.

An occluded front is a combination of two fronts that form when a cold front catches up and overtakes a warm front. The result is a mix of rain showers and thunderstorms.

A stationary front is the boundary between two air masses when neither is moving. Clear skies to partly cloudy skies may result, with occasional light rain.

The answer is "The Westerlies."Prevailing Westerlies are the winds in the middle latitudes between 35 and 65 degrees latitude. They tend to blow from the high pressure area in the horse latitudes towards the poles. These prevailing winds blow from the west to the east steering extratropical cyclones in this general manner.

A cold front moves faster than a warm air mass. The warm humid air is pushed up and results in a short period of heavy rain and possibly violent thunderstorms.

A warm front moves slower than a cold air mass. The warm air rises steadily above the cooler air mass and causes gentle rain showers for longer periods of time.

An occluded front is a combination of two fronts that form when a cold front catches up and overtakes a warm front. The result is a mix of rain showers and thunderstorms.

A stationary front is the boundary between two air masses when neither is moving. Clear skies to partly cloudy skies may result, with occasional light rain.

The answer is "stormy weather patterns"

A cold front moves faster than a warm air mass. The warm humid air is pushed up and results in a short period of heavy rain and possibly violent thunderstorms.

A warm front moves slower than a cold air mass. The warm air raises steadily above the cooler air mass and causes gentle rain showers for longer periods of time.

An occluded front is a combination of two fronts that form when a cold front catches up and overtakes a warm front. The result is a mix of rain showers and thunderstorms.

A stationary front is the boundary between two air masses when neither is moving. Clear skies to partly cloudy skies may result, with occasional light rain.