Tag Archives: definitions

Cloud Nine

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The phrase, “to be on cloud nine”, generally means that someone is so elated that they are walking on a cloud. With all the clouds in the sky, why did they choose number nine?

I have heard a number of origins for this popular saying, but the one that makes the most sense to me comes from the pioneering days of meteorology.  According to this theory, cloud number nine refers to a cumulonimbus cloud … the towering anvil shaped cloud of violent thunderstorms.

The story goes back to 1802 when an amateur British meteorologist named Luke Howard developed a basic nomenclature for clouds. He gave us names like cumulus, stratus, and cirrus.  His system followed the Linnaean ideas already in use with flora and fauna.  As the science of meteorology developed, different nations soon created their own weather vocabularies and classification systems.  This lack of consistency was creating confusion, especially since weather does not recognize national boundaries.  Before we had radar and satellites, the study of weather and  early forecasting relied on cloud identification and communications between weather stations.  To function properly and advance the science, these communications needed a uniform system of identification and measurement.

In 1896, an International Meteorology Conference was held in Paris to establish a uniform standard of cloud classification.  The committee built on Luke Howard’s Latin-based scientific names and set up the convention of grouping clouds according to their altitude. The product of this conference was the The International Cloud Atlas. This reference book used photographs and drawings to identify the ten cloud types agreed upon by the committee.  Cumulonimbus was number nine on their list.

A cumulonimbus is the tallest of all cloud types.  So, to be on cloud nine is to be on the highest cloud in the sky.  In a later edition of the Cloud Atlas, the order of list was re-arranged and cumulonimbus was moved to number ten.  The phrase, however, is still with us.

The International Meteorological Committee still exists today in the form of the World Meteorological Organization within the U.N.  They continue to publish The International Cloud Atlas.

The Ten Cloud Types

Photo Credit: Cloudloverclub

What is “Normal” Weather?

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As seasons change, months end, and years come to a close, we often hear about how that particular period’s weather compares to normal. You may wonder, what is “normal”?

“Normal”  refers to the 30-year average of a particular meteorolgical variable, such as temperature or precipitation, in a specific location.  This average is a statistical number that gives us an idea of what to expect as well as a point of reference for historical comparisons.  These figures are useful to scientists who study climate change and to industries, such as power and construction, who utilize the data for planning purposes.

The “normals” are calculated every decade for the previous 30-year period by the National Climatic Data Center (NCDC),  a division of the National Oceanic and Atmospheric Administration.  They have a mandate from Congress dating back to 1890 to “… to establish and record the climatic conditions of the United States.”   In addition, the United States is a member of the U.N.’s World Meteorological Organization (WMO).  As a member nation, we follow their guidelines for computing 30-year averages.

The NCDC recently released their new “normals” based on the years 1981 to 2010.

Ground-truth at the Early Bermuda Weather Stone

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Ground-truth, the eyewitness verification of atmospheric conditions, is an important part of weather reporting.  It supplements the data received from remote-sensing equipment like radar and satellites.

On a recent trip to Bermuda, an island that gets its fair share of severe weather, I came across the Early Bermuda Weather Stone in a park near Fort Scaur.  At first glance I thought this was a bit of local humor, but then it hit me.  This hanging rock is exactly what it claims to be, “…the perfect weather indication.”   In essence, it is a ground-truth indicator. The instructions on its sign sum up how to verify the current local atmospheric conditions.  It states:

  • A dry stone means… it is not raining.
  • A wet stone means… it is raining.
  • A shadow under the stone means… the sun is shining.
  • If the stone is swinging it means… there is a strong wind blowing.
  • If the stone jumps up and down it means… there is an earthquake.
  • If ever it is white on top… believe it or not… it is snowing.
The stone may be low tech, but its pretty accurate.

Photo Credit: MF at The Weather Gamut