The haystack standard currently defines a rather small set of tags that are related to weather. In reality, there are many weather point types that one might want to trend or express in haystack. The purpose of this document is to propose an enhanced set of tags for weather-related points for Project Haystack.

Your feedback is most appreciated.

All Tags

The following is a list of all current and proposed tags. They are discussed in more detail in the following sections. (* denotes existing tag)

• air temp (*)
• apparent temp
• barometric pressure
• cloudage
• humidity (*)
• precipitation
• solar irradiance
• sunrise (*)
• weather (*)
• weatherCond (*)
• weatherPoint (*)
• wetBulb temp (*)
• wind direction
• wind speed

Current Tags

The following are the proposed changes to existing weather tags.

weatherCond

The weather condition tag exists today and is expressed as a Number corresponding to a lookup table of 10 weather conditions. The new proposal will treat this tag as a Str enumeration with the following values:

• unknown
• clear
• partlyCloudy
• cloudy
• showers
• rain
• thunderstorms
• ice
• flurries
• snow

humidity

The humidity tag currently is currently expressed as a simple percentage. It will be changed so that the unit is %RH (percent_relative_humidity).

New Tags

The following lists the new proposed tags for modeling weather points.

barometric pressure

The barometric (or atmospheric) pressure. Measured in a unit pressure (e.g. millibar or inHg)

apparent temp

The perceived outdoor temperature, or the “feels like” temperature. Measured in a unit of temperature.

cloudage

The fraction of the sky obscured by clouds. This is also known as “cloudiness”, or “cloud amount”. Measured as a percentage (%).

precipitation

The amount of water substance that has fallen at a given point over a specified period of time. Measured in a unit of length (in. or mm)

solar irradiance

The amount of solar energy that arrives at a specific area at a specific time. For the purposes of weather data, this is measured at the earth’s surface. Measured in W/m2

wind direction

The wind direction. Measured in degrees.

wind speed

The wind speed. Measured in a unit of velocity.

Good work. Should fog (foggy?) be included as another enumeration of weatherCond? Also, should visibility be included as a tag? Measured in terms of distance (meters and miles)

I recommend to add the precipitation type (dizzle, rain, snow, hail, graupel etc.).

Another important indicator is the dew point; this should be added to the list.

In meteorology the barometric pressure is usually reduced to the sea level. Propably you need multiple barometric pressure tags: station pressure (QFE), pressure reduced to sea level (QFF), pressure reduced to sea level with standard atmosphere (QNH).

I think visibility makes sense as a weather point.

I think dew point also makes sense. I think it would be tagged as dew temp.

I'm not sure we need further qualification for barometric pressure. If a point is tagged as weatherPoint barometric pressure it should be considered to de facto mean pressure at sea level.

In terms of adding more weather conditions (foggy, types of rain etc.) I'd like to hold off on that temporarily. It's a little bit of a slippery slope to start going down that route. I've seen lists where there are dozens of weather conditions.

Would be delighted to see these additions. Have required barometric pressure and solar irradiance on a number of occasions. Happy with the proposed barometric pressure as de facto mean pressure at sea level.

Thanks. John

Hi Matthew,

I couldn't find a working group for this and I realize this was resolved quite a while ago, but I have three more suggestions to add as optional qualifiers for solar irradiance:

global: Global horizontal irradiance (when used with solar irradiance)

direct: Direct normal irradiance (when used with solar irradiance)

diffuse: Diffuse horizontal irradiance (when used with solar irradiance)

Steve