Meteorology 4

Pressure System Uneven heating around the earth leads to uneven areas of pressure as well these pressure systems can be identified as: Low Pressure Systems (cyclones) High Pressure Systems (anti-cyclones) Isobars are lines drawn on maps that have the same barometric pressure, they generally form concentric circles around the areas of high and low pressure systems. Low Pressure Systems Generally associated with cloudy and rainy conditions it is an area where air is rising because low pressure air naturally rises above the higher pressure air. Winds around low pressure systems rotate in a counterclockwise direction in the Northern Hemisphere and in a Clockwise direction in the Southern Hemisphere. High Pressure Systems Generally associated with colder, clear skies and light winds, temperatures get cooler at night as there is little cloud cover to trap the heated daytime air and winds around High Pressure systems rotate in a clockwise direction in the Northern Hemisphere and in a counterclockwise direction in the Southern Hemisphere Clouds and Precipitation Relative Humidity Ratio of the amount of moisture present in a volume air to the total amount of moisture that volume can hold at prevailing temperature and pressure for example 75% relative humidity means that the air is holding ¾ of the total moisture it is capable of holding at that temperature and pressure Dew Point The dew point is the temperature to which air must be cooled to become saturated at this temperature water in the air condenses as fog, dew, clouds, rain, snow, and hail. For instance if the dew point is 16 degrees and currently we're experiencing 20 degree weather; we don't expect any precipitation, but if the temperature drops to 15 degrees we can expect precipitation. Another useful aspect of the dew point is that it can often be used to determine at which altitude clouds will form since at higher altitudes the air gets cooler. A general rule is two degrees Celsius per 1000 ft. So at a certain altitude the air will reach the dew point temperature, and that is where you can expect clouds. Impact of Dew in RPAS Operation Dew is the formation of water droplets on surfaces and it is the biggest threat to RPAS as moisture can get into electronic components. You can however avoid dew by being aware of the dew point in your area. As well as watching for dew formation as temperatures drop and inspecting and cleaning your RPAS in those conditions.