@nasagoddard

A lake frequented by dinosaurs turned fertile farmland now often holds something else—air pollution and haze. Hundreds of millions of years ago, the Sichuan Basin in southwestern China held a huge freshwater lake. The lake has long since dried and the modern basin has become a land of rolling hills and fertile farmland. Air pollution and haze settle in the basin, as seen in this image from the Moderate Resolution Imaging Spectroradiometer on NASA’s Terra satellite. Why does this happen? During the winter, coal and wood burning for heat, industrial activity, vehicle emissions, and smoke from fires and dust storms can contribute to haze and poor air quality. Air pollutants collect in the basin when warm air moves over cooler, denser air, causing what meteorologists call a temperature inversion. Cold air from the mountaintops flows down and pushes up warmer air from the floor in the process. The warm air acts like a lid and traps pollutants near the surface. Learn more at the link in our bio! Image description: Satellite image of the Sichuan Basin in southwestern China. The basin is in the center of the image. It's shaped like an oval with flat top and bottom is light blue. Many small tributaries flow to the basin from all directions. Mountains are gray to the right of the basin and the land to the left is tan and green. White clouds speckle the top left and bottom right parts of the image.

February 08, 2023