As wildfires have intensified in recent years, scientists have begun to catalog the ways the massive events influence weather — but so far, all have looked at either enormous or relatively small scales.

But during 2018’s destructive fire season in California — at the time, the worst on record — Jiwen Fan started to wonder: Could the ever more frequent and intense fires raging in the western United States affect weather not just right next door, but as much as 1500 miles downwind?

Major weather patterns in the U.S. tend to travel from west to east along with the prevailing winds. Fan noticed that just a few days after California’s Carr Fire kicked off in mid-July — shockingly early in the expected fire season — a massive days-long storm struck the High Plains states like Wyoming and Colorado with flooding rains, baseball-sized hail, and 90-mile-an-hour gusts. The storm caused over $100 million in damages. Was it possible the two were connected?

Her team had the exact right tools to investigate the question. First, they dug through 10 years of weather and fire data to find examples of other big conflagrations (大火) occurring right before major storm events. The pairing was actually quite rare. That’s because storm season in the Central U.S. is centered around early summer; in the past, that season was winding down by the time wildfire season increased in August and September. But wildfires have been igniting earlier and earlier, pushed forward by climate change-driven drought and heat. Since 2010, the team found several big central storms that coincided with major Western fires.

They focused on a 2018 storm. Using a weather model that added in the effects of heat and smoke emitted from the burns, they simulated days-long storm event in several different ways. As the real situation had been, with massive fires burning in the West; as if those fires didn’t exist; and another set of experiments that included and excluded the effect of some smaller local fires that had been burning at the time.

The differences were dramatic: The combined impact from the faraway western fires and the local ones boosted the occurrence of heavier rainfall — where more than about 0.8 inches of rain fell in an hour — by 38 percent. The outbursts of big hail, with hailstones larger than two inches — nearly the size of a baseball— happened 34 percent more in the fiery conditions. But the far-off fires had a much larger effect.

“The impact is very significant,” says Fan. “That was a little surprising.”

【小题1】What’s the study of Jiwen Fan and her team mainly about?

A．The effect of conflagrations on the weather of other areas.

B．The scale of all the conflagrations.

C．The number of all the conflagrations that happened in 2018.

D．The cause of the California’s Carr Fire.

【小题2】Why was it rare for Fan’s team to pair big conflagrations with major storm events?

A．Because they were in lack of labor to dig through all the data.

B．Because storm season in the Central U.S. isn’t in line with the wildfire season.

C．Because wildfires usually take place in the early summer.

D．Because wildfires are pushed forward by big storms.

【小题3】How did Fan and her team conduct their study?

A．They invited other experts to do experiments with them.

B．They interviewed a lot of local people and analyzed the data they collected.

C．They simulated storm event in different ways by using a weather model.

D．They observed the real situations and calculated thoroughly.

【小题4】What does the last sentence “That was a little surprising.” imply?

A．The number of the big wildfires was beyond the team’s expectation.

B．The size of the hailstones was definitely incredible.

C．The occurrence of heavy rainfall shocked Fan’s team.

D．The conflagrations did have great effect on the occurrence of storm in other areas.