In detail, why is air/ground temperature, soil moisture, relative humidity, and dew point different at multiple sampling sites within the same area?

As explained below.

Explanation:

Water content is the quantity of water that is contained in a matter such as soil, crops, and wood, etc. Its expressed in ratios and ca range from 0 i.e complete dry to porosity of material saturation, water classification use capillary condensed water in small pores, relative humidities, moisture consist, liquid water becomes more and more important, depending or not depending. Dew point is represented by the temperature in the air and air has high and lower temperatures. Humidity factors remain constant Temperature over the night and the day are known to vary depending on the altitude and seasonal extents. It all depends on the level of air saturation and hence there exists a temporal and seasonal variability.  Thus the samples don't tend to be the same at all places in the areas that have different diurnal and annual fluctuations in the heating and cooling patterns experienced over different places on earth.