How earths surface affects the characteristics of an air mass?

Answer 1

The earth's surface is so important to the characteristics of an air mass that I could write a short story. But I want. First if the surface is a cold ocean or sea then the lower levels of the atmosphere become very humid, but frontal instability over such seas can result in massive winter storms that bring rain and snow to land areas. If nothing else the moisture of the cold seas bring lots of low clouds and sometimes fog as along the California coast. The warm seas bring more unstable air into the atmosphere contributing to the formation of thunderstorms and hurricanes. The total amount of water vapor in the air over warm seas is much greater.

Any land surface that is heated by the sun will change the air mass, as the shortwave radiation from the sun is radiated from the land surface to the atmosphere. This can result in daytime cloudiness to develop and even showers or rain, snow, or thunderstorms. Sometimes warm air will move over colder ground as in the winter or at night and the moist ocean air is cooled near the surface forming stratus clouds or fog.

Mountains change the air masses significantly. If air is flowing against a mountain range (windward side) it will be forced to rise and cool. If the air is unsaturated the air will cool at 5.5 degrees Fahrenheit (F) per 1000 feet as it rises. Once it cools to saturation, it cools around 3 degrees per 1000 feet, and clouds form, perhaps with rain or snow or thunderstorms. As the air descends down the other side of the mountain (leeward side) the air is drier and sinks and warms at 5.5 degrees per 100 feet. Thus on the leeward side the air becomes warm and dry. This can result in a desert if the winds blow this way most of the time.

Sea breezes form along the coast during the daytime and cool the land, but at night if the ocean stays the same temperature and the land cools more than the water a land breeze forms and the wind blows out to sea.

Concerning winds, flat land surfaces as in America's Great Plains allow the wind friction to be minimal and the wind blows strong. Oceans being smooth water (at least initially) give less friction than the land unless large waves develop. Mountainous terrain will cause more friction on the land resulting in quite variable wind speeds. More gustiness will be apparent. Winds that may be light near the higher mountains will find passes to rush through with great speeds. Sometimes we cause these gap winds.

If the land is dark soil as in the good farming land, the soil will absorb the solar short wave radiation easily. The air then heats up around this type of terrain, but plants putting moisture into the air have a cooling effect. Forests have a cooling effect from the evaporation of moisture and the shading of the air mass near the surface. Deserts have no way of cooling the air during the day without plants or clouds. But in the low layers the desert can cool off rapidly after sunset.

Cities hold heat at night because of the buildings, streets, and sidewalks. This is called the heat island effect.

Air that sits over land during the dark winter of the polar regions of ice and snow covered areas in the winter become extremely cold in the lower atmosphere. In the Northern Hemisphere we see these airmass domes come south and name them based on where they come from. Arctic air that can bring the coldest air of the winter.

Give me some air that comes from a tropical ocean and I'll be happy. We call these Maritime tropical.