hOW DOES THE LACK OF ATMOSPHERIC MOISTURE IN cALIFORNIA'S mOHAVE dESRT CAUSE A LARGE DAILY TEMPERATURE CHANGE

Answer 1

A small amount of moisture (water vapor) in the air means a low dewpoint. On a clear, calm night, the temperature usually falls to around where the dewpoint is, because it can't fall anymore (well, it can, but little more because the water in the air has to condense first, that's why you see fog in the morning sometimes that forms overnight).

Anyway, in short - the low dewpoint means the temperature can fall pretty far at night from the high temperature for that day (which in the desert can be high due to strong heating from the sun).

Answer 2

Excellent question. Water vapor is the atmosphere's most significant green house gas. When it is present, visible sunlight passes through but the infrared radiation from the earth's surface is absorbed by the water vapor and then reradiated back down to the earth's surface. This atmospheric constituent helps moderate the otherwise rapid loss of heat (infrared radiation) at night which causes such large diurnal temperature fluctuations. This is also the reason why on nights when we have clouds that the surface temperature doesn't drop as low as it does on clear nights.

Answer 3

Lack of moisture means a "thinner" atmosphere, hence, the temperature rises and falls faster over a 24 hour period.

Answer 4

Yes, with less moisture, you with have a greater range in temperature for several reasons:

1. Less moisture in the atmosphere will result in a lower chance of clouds forming during the day. Less clouds results in more solar heating (sunshine) in the day.

2. Less clouds at night, when combined with light winds, will result in excellent radiational cooling. The blind you with science explanation: With light winds, heat energy will radiate upwards from the surface with less of a chance of it being caught up in turbulence that will mix some of the heat back towards the ground. And if there are clouds, some of these energy escaping from the lower levels will be absorbed. The clouds will then release a portion of that energy back towards the surface.

3. With a dry air mass, the dew point will be very low. Therefore the air mass will cool rapidly most of the night with a less chance of it cooling to the point of condensation. Blind you with science explanation: The air mass will have to cool much lower in order for it to reach saturation. This means there is less likely for condensation to occur overnight. Condensation, the process of water changing from the gas phase to liquid phase, will result in the release of heat energy to the surrounding air mass. This will slow the cooling process. With drier air, less heat energy is being release as the ratio of evaporation will be much higher than the ratio of condensation.

Summary: With less clouds, you will get more sun and higher temperatures during the day. With a period of less wind in a dry atmosphere, air mixing will be less of a factor. With little or no clouds, the heat energy have no clouds to interfere with the escaping heat energy built up during the day. The drier air will also means the air will continue to cool at a higher rate for most of the night as the cooling process is more efficient.