Atmospheric Physics and Humidity

Rain gauge can accurately measure the rainfall without any loss due to evaporation. It is an instrument used for determining the depth of precipitation that occurs over a unit area. Thus, it measures rainfall. One liter of rainfall per meter squared is equivalent to one millimeter of measured precipitation. A funneled aperture of 150-170 cm is found in standard rain gauges. They are designed as a simple passive collector. A graduated measuring glass is used for determining the amount of precipitation. For the measurement of rainfall, the rain gauze should be placed 30 cm above the ground to prevent the splashing of rainwater.

Isotherms are lines drawn on a map connecting points that have the same temperature. Isobars connect points of equal pressure, and isohyets connect points of equal rainfall.

Hygrometers measure humidity, specifically relative humidity which is the ratio of current moisture content to maximum possible moisture at that temperature. These readings are essential for weather forecasting and comfort assessment.

With increasing altitude the the temperature decreases and atmosphere becomes less dence. The direct source of atmospheric heat lies at the surface of the earth,the higher we ascend in the atmosphere,the lower the temperature are.The lower layers of the air at or near the surface are dence cause it contains more water vapour,more water particles and more dust particles than the upper air.Since these substances absorb a large amount of terrestrial radiation,the lower part of the atmosphere has higher temperature and dence than upper part of the atmosphere.

• Normally when we move up the altitude the temperature decreases with a certain rate called the normal lapse rate.
•  However, sometimes there is inversion or change in this property and the temperature after a certain height starts to increase rather than decreasing. This is called inversion of temperature, thus option C is correct. 

As the temperature of the air increases its capacity to hold moisture increases while with the decrease in the temperature of the air, its capacity to hold moisture decreases. Thus the capacity of the atmospheric air to contain water vapor is directly proportional to its temperature. Hence option B is correct.

In the troposphere, which is the lowest layer of the atmosphere where weather occurs, both atmospheric pressure and temperature decrease as altitude increases.

Wind is the horizontal movement of the air. The differences in air pressure within our atmosphere causes the wind. Under high pressure, air moves towards area of low pressure. The greater the difference in pressure, the faster the air flows. Wind is described with direction and speed. The direction from which the wind is blowing describes the direction of wind.

Wind is been defined as air in horizontal motion caused by difference in pressure. There are two type of movement in the atmosphere : horizontal movement and vertical movement. Vertically moving air columns are known as currents. Winds are the means by which uneven distribution of pressure over the globe is balanced out .

The adiabatic lapse rate for wet (saturated) air is approximately 0.6 degrees Celsius per 100 meters, which is lower than the dry adiabatic lapse rate due to the release of latent heat during condensation.

Relative humidity is defined as the ratio of the actual water vapor content to the maximum possible water vapor content at a given temperature. It is not a direct measure of the actual vapor content itself, which is defined by absolute humidity or vapor pressure.

In Polar Regions, the air is extremely cold, which significantly lowers the air's capacity to hold water vapor. Consequently, even small amounts of moisture result in high relative humidity, often reaching saturation levels near 100 percent.

Actual vapor pressure is a measure of the amount of water vapor in the air. If the temperature increases but no water vapor is added or removed, the amount of water vapor remains constant, and thus the actual vapor pressure stays the same.

Humidity is the general term used to describe the amount of water vapor or moisture present in the air.

The unit of relative humidity is the percentage. It is the ratio of the current absolute humidity to the maximum humidity for that temperature. A hygrometer is a device which is used measure relative humidity. When the air is fully saturated with water vapor and cannot hold any more water vapor, the relative humidity is 100%.