Scientific approach to atmospheric conditions safeguards Yan'an's orchards

For experienced apple growers in Yan'an, a city in northwestern China's Shaanxi province, the toughest challenges of their jobs aren't planting techniques or irrigation systems, but the unpredictable late-spring frosts and sudden hailstorms that threaten to wipe out a year's worth of hard work in a single night.

In recent years, farmers across the city's rugged apple-producing hills have increasingly turned to modern meteorological tools, including portable weather stations, artificial hail suppression systems, and weather index insurance, to protect their crops and reduce climate-related losses.

At an orchard in Zhidan county in July, rows of apple trees stood lush and healthy despite enduring three recent frosts. The resilience was thanks in part to a small lantern-shaped device hanging from the branches — a "mini weather sentry" that monitors real-time temperature and humidity, local officials said.

"This little gadget is a game-changer," said Zhang Hong, an official at the county's agriculture and rural affairs bureau. "In the past, farmers would tie thermometers to trees and check them with flashlights in the freezing night. Now, they can stay warm at home and monitor everything through the 'Shaanxi Weather' app or the 'Ping'an Weather' mini program."

The devices are part of two-factor orchard weather stations deployed at different altitudes to offer localized data. These stations alert growers to freezing temperatures during the critical blooming season in April and May, giving them time to take preventive measures such as lighting smudge pots to create protective smoke around the trees.

"Zhidan county has so far deployed 380 such stations," Zhang said.

In Yan'an, 475 six-factor smart weather stations and 1,670 two-factor orchard weather sensors have been installed in recent years. According to the Yan'an Meteorological Bureau, the average distance between monitoring stations has been slashed from 23 kilometers to just 4, enhancing the accuracy of forecasts and frost warnings.

While frost is a lingering threat in the spring, hailstorms pose a year-round risk, particularly in Wuqi county.

"For apple farmers, hail is a nightmare," said Liu Yue, an orchard owner in Wuqi. "A flawless apple sells for up to 6 yuan per kilogram, but one hit by hail won't fetch a single yuan."

To combat the risk, Wuqi launched a pilot hail suppression program in 2023. The project introduced advanced cloud-seeding equipment, automated rocket systems, and an artificial intelligence-enabled early warning command platform. The upgraded system allows for rapid detection, intelligent forecasting, and automated cloud seeding at precise locations and altitudes.

"The key to successful hail suppression is to act early — when the hail is still just ice crystals," said Yang Guang, a technician with the Wuqi Meteorological Bureau. "This year, we've conducted more than 30 suppression operations, and the results have been very promising."

In tandem, the Yan'an Meteorological Bureau has upgraded automated ground hail prevention equipment, enabling safer and more efficient storm mitigation efforts.

However, even with cutting-edge equipment, some damage is unavoidable when extreme weather strikes.

In May, Zhang Jun, a first-time apple grower in Wuqi, saw his 3-hectare orchard suffer a devastating frost. "We were expecting about 50 metric tons of apples," he said. "Now we might just get 10."

Luckily, Zhang had enrolled in a pilot weather index insurance program, targeting frost in the blossom season, introduced this year in Wuqi and neighboring Luochuan county. The policy, triggered by specific temperature readings, allowed him to receive a quick payout.

"That night, the orchard's temperature sensor recorded — 1.8 C," said Zhang Haihang, a representative from the People's Insurance Company of China in Wuqi. "We sent a loss adjuster the next morning. The system calculated a compensation of 6,075 yuan per hectare."

Unlike traditional crop insurance, which often requires a lengthy damage assessment after harvest, the index insurance model speeds up compensation based on verified meteorological data.

"This model brings insurance closer to farmers," said Sun Zhihui, chief technician at the Yan'an apple meteorological science and technology backyard. Sun and his team developed the weather index system specifically for apple farmers in the region.

"Previously, growers had to wait until harvest season for any compensation, and the process was slow and uncertain," Sun said. "Now, with automatic payouts triggered by precise weather events, more insurers are willing to participate, and more farmers are covered," he added.

As climate variability intensifies, the city's apple industry, which employs over one million people, is banking on meteorological innovation and public-private cooperation to protect its future.

Wang Weigang, head of the Yan'an Meteorological Bureau, said the city will continue to strengthen monitoring, improve forecasting accuracy, and expand intelligent services tailored to apple growers.