US President Donald Trump landed in Beijing today under clear sunny sky as China has virtually driven away the smog hovering over the city in the last few days with emergency measures.<br/><br/><br/>Following the smoggy weather in the past few days Beijing today woke up to a beautiful sunny morning.'<br/><br/>China's environment ministry had ordered the local authorities to lift the orange alert for air pollution saying that air quality had improved thanks to emergency measures.<br/><br/>China has a four-tier colour-coded warning system for severe weather, with red being the most serious, followed by orange, yellow and blue.<br/><br/>But as authorities adopted a raft of emergency measures to meet the smog challenge, most of the areas experienced slight air pollution or even good air, state-run Xinhua news agency reported earlier.