SHANGHAI - When Eric Chen, a local visitor, saw lightning strike the ground in the distance, he was wowed, along with others, while standing near the exit of Shanghai World Expo's China Pavilion at 6:05 pm Tuesday.

The rain was delayed another five minutes before falling. Chen and most people in the park decided to let the rain fall on them. "Raindrops feel great when you are nearly parched to death."

When the rain began, visitors started to open their umbrellas. Those without umbrellas did not hurry to take shelter; most of them moved slowly as they enjoyed the cool rain or were sluggish from a day of walking at the Expo.

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Down the square near the Japan Pavilion, thousands of people were queuing in a line under a shelter. The heat vaporized rain drops and formed what wondering passers-by called a "mysterious line of fog".

As the rain stopped about 6:40 pm, the park began broadcasting news, "According to the municipal meteorological bureau, the orange heat alert has been cancelled," it was reported.

Readings from what is being called the world's largest thermometer, standing at 165 meters high in the park, dropped from above 37 Celsius degrees to about 31 degrees.

"The weather is good now. I wonder if it can last tomorrow," Eric said. Although a local resident, he is renting a motel room nearby at the rate of about 1,000 yuan ($147.6) a night. "Even if it cools down tomorrow, it will only mean more people and longer queues."

As of 6:30 pm, 327,800 people had visited the Shanghai World Expo on Tuesday. Many of these visitors begin queuing at the gate as early as 5 am. In addition to the wait at the park's gate, to enter the most popular pavilions, like the Saudi Arabian Pavilion and Oil Pavilion, can take more than three hours waiting in lines.