14．Keeping an Eye on the Weather
Weather forecasters don't just look out of the window to prepare the report you see on TV or hear on the radio．They use a high-tech weather information network located all over-and above
-the globe．Satellites orbit Earth all the time．Planes and balloons go up daily to collect data．Weather stations in almost every country on the earth contribute data．
As you've noticed，forecasters sometimes make mistakes．A forecast is only a prediction．It is based on what's happening now．However，nature doesn't always follow a predictable pattern，so a forecast is only an educated guess，not a certainty．
Weather satellites remain in fixed positions 22，000miles above the equator （赤道）．Together，their cameras can photograph the entire earth，except the poles．Other satellites follow north-south and south-north routes from pole to pole．
The long tails of weather balloons are equipped with radiosondes，which measure temperature，air pressure，and humidity in the atmosphere．Some balloons can reach as high as 90，000feet to collect data．
Weather monitoring equipment is attached to airplanes．These planes can fly directly into storms to take measurements．
About 10，000weather stations around the world send reports every three hours to 13weather centers operated by the World Meteorological Organization （世界气象组织）．
Probably the most familiar piece of weather equipment is the weather vane．It's certainly one of the oldest．Weather vanes have been around since the ninth century．They indicate the direction the wind is blowing．
Radar equipment sends signals into clouds．These signals are then changed into images on radar screens，allowing meteorologists to track storms．
Other stations float at sea and send data to satellites．
64．Why do forecasters sometimes make mistakes？（不多于9个词）Because nature doesn't always follow a predictable pattern
65．What are measured by weather balloons equipped with radiosondes？（不多于9个词）
Temperature，air pressure and humidity
66．What does the weather vane indicate？（不多于6个词）The direction of the wind
67．What does the passage mainly talk about？（不多于6个词）Weather information network．
