To read the pressure on a station model, you need to decode the three digits in the upper-right-hand corner, which represent the last three digits of the station's sea-level pressure in millibars (mb), expressed to the nearest tenth of a millibar.
Steps to Decode Sea-Level Pressure:
-
Identify the Three Digits: Locate the three digits in the upper-right corner of the station model. These are the key to unlocking the pressure reading.
-
Insert the Decimal: Add a decimal point before the right-most digit. For example, if the digits are 123, this becomes 12.3.
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Add a Leading '9' or '10': You'll need to add either a '9' or '10' to the left of the number you obtained in step 2. Here's the rule:
- If the resulting number is less than 950.0 mb or greater than 1050.0 mb, add a "10".
- Otherwise, add a "9".
Examples:
| Digits on Station Model | Insert Decimal | Add '9' or '10'? | Decoded Pressure (mb) |
|---|---|---|---|
| 123 | 12.3 | 9 + 12.3 | 1012.3 |
| 876 | 87.6 | 9 + 87.6 | 987.6 |
| 005 | 00.5 | 10 + 00.5 | 1000.5 |
| 456 | 45.6 | 9 + 45.6 | 945.6 |
By following these steps, you can accurately determine the sea-level pressure recorded at the weather station. Remember, the three digits represent the last three digits of the sea-level pressure in millibars to the nearest tenth.
