Main components of the lower atmosphere

The lower atmosphere is mainly composed of nitrogen, oxygen, water vapor, argon and carbon dioxide.

Components of the lower atmosphere

1. Dry air. Main ingredients: N2: the basic component of living organisms; O2: the necessary substance for all living things to maintain life activities; trace ingredients: CO2: the basic raw material for photosynthesis of green plants, which keeps the ground warm; O3: absorbs ultraviolet rays and protects organisms on the earth from immunity. Damaged by excessive ultraviolet rays;

2. Water vapor: an important role in weather changes;

3. Solid impurities: as condensation nuclei, it is a necessary condition for cloud formation and rain.

Changes in the composition content of the lower atmosphere

1. N2 and O2 contents remain basically unchanged

2. CO2 content increases

Reasons : Burning fossil fuels emits large amounts of CO2 into the atmosphere; deforestation, especially the destruction of tropical rainforests, rapidly reduces the amount of carbon dioxide absorbed and fixed by forests.

Consequences: Rising sea levels; causing changes in precipitation and wet and dry conditions around the world. O3 content decreases.

Moisture Detection

In the summer of 2006, Doppler weather radar was first used to detect water vapor in the lower atmosphere. Data on water vapor in the lower atmosphere help forecasters determine the location and timing of an approaching storm minutes to hours in the future. The researchers measured changes in the speed of radar signals caused by refraction, which can reveal the presence or absence of atmospheric moisture.

If the trial is successful, the refraction technology could be added to the National Weather Service's National Doppler Radar Network within a few years. Significant differences in water vapor are conducive to the formation of strong storms, but the location of such significant differences is difficult to determine before the storm develops. The National Weather Service's radar measures rainfall and wind, not water vapor.

Moreover, the spatial distance between weather stations and detection balloon water vapor measurements is more than 80-160km. In fact, there are no routine measurements of lower atmospheric water vapor. When meteorologists use Doppler radar to track storms, they usually detect signals that bounce off raindrops, hailstones or snowflakes and then reflect them back. The strength of this return signal reflects the intensity of rain, hail and snow, while changes in signal frequency contain information about the wind.

In the meantime, the researchers added another factor - the speed of the radar signal. They used fixed targets, such as power lines and missile silos, to determine the magnitude of the acceleration and deceleration of radar signals caused by water vapor. Researchers fill in the obtained refractive index data on the map to determine the location of the water vapor. REFRACTT

The research idea of ??REFRACTT was proposed by Fredic Fabry of McGill University who is a visiting scholar at NCAR. Forecasters at the Denver Weather Bureau have used REFRACTT data to monitor tornadoes in northeastern Colorado. Larry Mooney, chief expert at the Denver Weather Bureau, pointed out: Water vapor in the lower atmosphere is a key factor in producing all kinds of weather, especially in the summer.

REFRACTT chief scientist Rati Roberts pointed out that no one has ever obtained water vapor data with such high resolution, and believes that these data will be of great help to heavy rain forecasts.