The weather forecast is so “interpreted”

From 19:30 in the evening, waiting in front of the TV to watch the weather forecast, and opening the eyes in the morning to turn on the weather reminder that automatically appears on the screen, the weather forecast has changed a lot in just a few decades. What changed is The terminal is the form. What remains unchanged is our people’s emphasis on weather forecasting. The previous article introduced “how weather forecast is made”. Today I will take you to a comprehensive understanding of the relevant process and knowledge points of weather forecast products delivered to you.

Contents of the weather forecast: phenomena and elements
Usually the weather forecast we all receive is composed of two parts, one is called weather phenomenon and the other is called meteorological element.

Weather phenomena are meteorological-related physical phenomena that occur in the atmosphere and on the ground. These phenomena can be roughly divided into five categories: one is the phenomenon of precipitation that occurs all year round; the other is the ground condensation that occurs only when the weather becomes cold. Freezing phenomena, including dew, frost, fog, rain; third, visual range obstacles common in winter and spring, such as fog, haze, sand, and dust; fourth, summer-based thunder and lightning phenomena; fifth, such as high winds and tornadoes , Snow, ice and other phenomena.

Meteorological elements are those basic physical quantities and basic weather phenomena used to represent the state of the atmosphere. It mainly includes: air temperature, air pressure, air humidity, wind speed and direction, visibility, cloud shape, solar radiation, precipitation, etc. Meteorological elements are closely related to people’s production and life, and have a huge impact on the entire human activity.

In ordinary weather forecasts, only the highest and lowest temperatures; maximum and minimum relative humidity; wind direction and wind; sky conditions and possible weather phenomena are generally listed.

The weather forecast is different, which one should I trust?
Have you ever had this confusion: “Why is the weather forecast on the mobile phone different from that issued by the Meteorological Bureau?” There are two main reasons for this difference: First, the information provider (such as the weather forecast on the mobile phone) APP) The channels for obtaining weather forecasts are different. APP uses numerical forecast when making weather forecast. There are different models for numerical forecasting, such as European Center, Japan, Canada, and so on. The design schemes are different, and the final data are different. Some information providers do not have forecasters and only publish the results based on calculations such as numerical values, so they are different from the weather forecast issued by the meteorological department.

Second, the time at which the information provider updates the weather forecast is not necessarily synchronized. Under normal circumstances, the meteorological station will publish the weather forecast to the society twice a day for the next 24 hours, once before 7 am and once before 5 pm. According to the regulations of the meteorological department, once a new weather forecast is generated, the old weather forecast is naturally invalidated. If the time for updating the weather forecast between the information providers is not synchronized, the weather forecast for a certain place may be different in a certain period of time.

China’s meteorological law stipulates that the state implements a unified release system for public weather forecasts and severe weather warnings. Meteorological stations under the competent meteorological authorities at all levels shall issue public meteorological forecasts and catastrophic weather warnings to the society in accordance with their duties, and shall supplement or correct them in a timely manner in accordance with weather changes. No other organization or individual may release public weather forecast and severe weather warning to the society.

Different classifications, giving you more choices
Everyone knows that the weather forecast gives a detailed forecast of weather phenomena and meteorological elements at a certain time in the future. Therefore, “some time in the future” has become the time classification standard for weather forecast. Weather forecast, according to the length of forecast time, can be divided into: near-term forecast (forecast), short-term forecast, medium-term forecast, long-term forecast and ultra-long-term forecast. In general, a 0 to 2 hour forecast is called a “nearcast (current forecast)”; a 0 to 12 hour forecast is called a “short-term forecast”; a forecast for the next 1 to 3 days is called a “short-term forecast” “; Forecast the weather forecast for the next 4 to 10 days, called” medium-term forecast “; forecast for the forecast of more than 10 days, month, quarter, and year is called” long-term forecast “; forecast for more than one year is called” ultra-long-term forecast ” “.

Short-term forecast requirements are more detailed and specific, for example: Will it rain the next day? When does it rain? Rainfall, cloudiness, temperature, wind, etc. Longer-term forecasts can only infer overall weather trends, such as: Is this year dry or waterlogged? This year’s spring ploughing and spring sowing are low temperature, cloudy, or warm, sunny? One of the major characteristics of meteorological forecasting is that the shorter the time distance of the forecast, the higher the accuracy. Based on continuously updated observations, meteorologists can revise previous forecasts. You can choose to see different time-effect forecasts according to your specific needs.

Special time term: What white do you mean by white?
When you watch TV weather programs or check mobile phone weather messages, the time mentioned in the weather forecast is described in terms of “day, night, morning, and afternoon”. So, what time is the so-called “daytime”?

In fact, the time concept of weather forecasting has a strict alignment. Take our most common 24 hour weather forecast released in the afternoon as an example, the valid time of the forecast is from 20:00 on the day to 20:00 on the next day. Among them, this night refers to 8:00 at the same day to 8:00 on the next day. Tomorrow Daytime refers to the next day from 8am to 8pm. We are accustomed to setting daylight to dark as daytime, but the weather forecast is divided into 8 points to 8 points.

More detailed time divisions are as follows: morning means 5 to 8; morning means 8 to 11; noon means 11 to 13; afternoon means 13 to 17; evening means 17 to 20 Point; midnight refers to 23 o’clock to 1 o’clock the next day. According to this time division table, we can combine the concept of time in the weather forecast with the concept of time in daily life to more accurately grasp the specific time period where the weather may change.

No more accurate, more accurate
There are errors in the weather forecast, and accuracy is relative. As the old saying goes, “the sky is unexpected”-the atmospheric environment is changing rapidly, and modern human technology cannot accurately grasp it. We can only continue to correct and reduce errors. In the 1990s, China’s climate forecasting business has just started, and the forecast accuracy rate is about 60% to 65%. Twenty years have passed, and the accuracy of China’s climate prediction has increased by more than ten percentage points, between 70% and 80%. This is a great improvement.

The accuracy of different types of weather forecasts is different. Weathers with large spatial scales and long time scales, such as high temperatures and cold waves, have higher forecast accuracy. The 24-hour weather forecast and the highest and lowest temperature forecasts across the country can achieve “eight or nine inseparable.” However, some weather events occur suddenly and have strong local characteristics. This kind of weather forecast is more difficult and less accurate. For example, strong convective weather, that is, hail, heavy rainfall, strong lightning, strong winds, tornadoes, etc. that occur in a short period of time, their forecast accuracy is very low.

Human understanding of the atmospheric system is still in its infancy, and the history of human weather forecasting is only over 160 years. There is still much room for development of weather forecasting technology in the future. For weather forecasting, there is no most accurate, only more accurate!