{
  "schema": "nephos.example-analysis.v1",
  "analysis_id": "NEP-EX-002",
  "object": {
    "title": "Cloud Study",
    "artist": "John Constable",
    "date": "1822-09-21",
    "inscription_verbatim": "Sep 21 1822 past one o'clock looking South wind very fresh at East, but warm.",
    "inscription_source": "YCBA catalogue Inscription(s)/Marks/Lettering field; the original is on the back of the panel, now covered by a conservation backboard.",
    "place": "Hampstead, London (series localization per YCBA curatorial text; coordinates are the analyst's, not the museum's)",
    "accession_number": "B1981.25.116",
    "collection": "Yale Center for British Art, Paul Mellon Collection",
    "medium": "Oil on paper laid on panel",
    "dimensions": "11 1/4 x 19 in (28.6 x 48.3 cm)",
    "rights": "Public Domain / CC0 1.0",
    "record_url": "https://collections.britishart.yale.edu/catalog/tms:627",
    "iiif_manifest": "https://manifests.collections.yale.edu/ycba/obj/627"
  },
  "claims_on_the_object": [
    {
      "id": "date",
      "claim": "Sep 21 1822"
    },
    {
      "id": "time",
      "claim": "past one o'clock"
    },
    {
      "id": "view",
      "claim": "looking South"
    },
    {
      "id": "wind",
      "claim": "wind very fresh at East"
    },
    {
      "id": "warmth",
      "claim": "but warm"
    }
  ],
  "capture": {
    "capture_id": "ycba_627_recto_cropped",
    "source_asset": "assets/constable/source/cloud-study-1822-recto.jpg",
    "source_sha256": "45172bb63160087859f20e084060ed82acad991c1ee74c174cca9e1e7f3145f1",
    "source_dimensions": [
      3660,
      2167
    ],
    "source_iiif": "https://images.collections.yale.edu/iiif/2/ycba:a1a011a9-da67-4438-97e4-afe1151cd62b/full/full/0/default.jpg",
    "region_assets": {
      "upper_blue": "assets/constable/derived/constable-upper-blue.jpg",
      "cumulus_left": "assets/constable/derived/constable-cumulus-left.jpg",
      "grey_mass_right": "assets/constable/derived/constable-grey-mass-right.jpg",
      "haze_bed": "assets/constable/derived/constable-haze-bed.jpg"
    },
    "region_metrics": {
      "upper_blue": {
        "mean_rgb": [
          136,
          155,
          155
        ],
        "mean_hex": "#889b9b",
        "mean_saturation": 0.136,
        "mean_relative_luminance": 0.592,
        "luminance_standard_deviation": 0.033,
        "pixel_count": 798708
      },
      "cumulus_left": {
        "mean_rgb": [
          144,
          152,
          143
        ],
        "mean_hex": "#90988f",
        "mean_saturation": 0.1,
        "mean_relative_luminance": 0.586,
        "luminance_standard_deviation": 0.05,
        "pixel_count": 1427400
      },
      "grey_mass_right": {
        "mean_rgb": [
          161,
          160,
          143
        ],
        "mean_hex": "#a1a08f",
        "mean_saturation": 0.122,
        "mean_relative_luminance": 0.624,
        "luminance_standard_deviation": 0.055,
        "pixel_count": 732550
      },
      "haze_bed": {
        "mean_rgb": [
          159,
          159,
          142
        ],
        "mean_hex": "#9f9f8e",
        "mean_saturation": 0.118,
        "mean_relative_luminance": 0.619,
        "luminance_standard_deviation": 0.038,
        "pixel_count": 663507
      }
    },
    "painted_sky_fractions": {
      "opaque_cloud": 0.579,
      "thin_veil": 0.167,
      "clear_blue": 0.254
    },
    "cloud_mask_overlay": "assets/constable/derived/cloud-mask-overlay.png",
    "cloud_mask_note": "Capture-specific blueness heuristic (strongly blue paint reads as clear sky, weakly blue as thin veil, warm or neutral as opaque cloud); it measures this digitization's paint colors, not the 1822 atmosphere.",
    "x_radiograph_iiif": "https://images.collections.yale.edu/iiif/2/ycba:08a9dda3-efd8-428a-9751-541a9957dabe/full/full/0/default.jpg",
    "x_radiograph_note": "YCBA x-radiograph (7/19/2022, 30 kV, 5 mA, 105 s): lead-white cloud masses are radio-opaque and register bright."
  },
  "solar": {
    "library": "Skyfield 1.55",
    "ephemeris": "JPL DE440",
    "site_assumption": {
      "latitude_degrees_north": 51.56,
      "longitude_degrees_east": -0.165
    },
    "time_interpretation": "'past one o'clock' read as 13:00-14:00 local mean time; LMT at 0.165 W trails UTC by about 40 seconds.",
    "table": [
      {
        "local_mean_time": "13:00",
        "altitude_degrees": 37.308,
        "azimuth_degrees": 201.341
      },
      {
        "local_mean_time": "13:30",
        "altitude_degrees": 35.268,
        "azimuth_degrees": 210.301
      },
      {
        "local_mean_time": "14:00",
        "altitude_degrees": 32.616,
        "azimuth_degrees": 218.763
      }
    ],
    "summary": "Between 13:00 and 14:00 LMT the sun stood 37.3 to 32.6 degrees above the horizon at azimuth 201 to 219 degrees - south-southwest, above and to the right of a painter looking south.",
    "disposition": "consistent, not independently residual-tested",
    "limit": "A pure sky with no horizon yields no measurable painted solar direction, so no painted-versus-computed angular residual is reported."
  },
  "weather": {
    "dataset": "NOAA-CIRES-DOE 20th Century Reanalysis v3",
    "inputs_from_painting": 0,
    "grid_cell": {
      "latitude": 52.0,
      "longitude": 0.0,
      "resolution_degrees": 1.0
    },
    "date": "1822-09-21",
    "utc_hours": [
      "06:00",
      "09:00",
      "12:00",
      "15:00",
      "18:00"
    ],
    "total_cloud_cover_percent": {
      "ensemble_mean": [
        51.0,
        57.0,
        60.0,
        63.0,
        57.0
      ],
      "ensemble_spread": [
        39.21,
        37.61,
        31.72,
        34.0,
        34.42
      ]
    },
    "u_wind_10m_ms": {
      "ensemble_mean": [
        -2.110466,
        -4.6705565,
        -4.9793115,
        -4.8147798,
        -3.3837693
      ],
      "ensemble_spread": [
        2.7707422,
        3.5591502,
        3.6187677,
        3.3017032,
        2.5360978
      ]
    },
    "v_wind_10m_ms": {
      "ensemble_mean": [
        -2.8453445,
        -2.6773949,
        -2.9898705,
        -3.5372376,
        -3.169906
      ],
      "ensemble_spread": [
        1.6746607,
        2.3651502,
        2.5429246,
        2.4677033,
        1.670438
      ]
    },
    "air_temperature_2m_K": {
      "ensemble_mean": [
        282.4222,
        285.5312,
        287.18015,
        287.0742,
        284.94043
      ],
      "ensemble_spread": [
        2.0250695,
        1.4225051,
        1.7017908,
        1.7868588,
        1.3687993
      ]
    },
    "at_target_1300_utc": {
      "cloud_cover_percent": 61.0,
      "cloud_cover_spread_pp": 32.5,
      "wind_speed_ms": 5.86,
      "wind_speed_range_1sigma_ms": [
        1.56,
        10.18
      ],
      "wind_from_degrees": 57.2,
      "wind_from_range_1sigma_degrees": [
        13.9,
        85.6
      ],
      "wind_from_compass": "ENE",
      "air_temperature_c": 14.0,
      "air_temperature_spread_k": 1.7
    },
    "query_urls": {
      "tcdc_mean": "https://psl.noaa.gov/thredds/dodsC/Datasets/20thC_ReanV3/miscSI/tcdc.eatm.1822.nc.ascii?tcdc%5B2106:1:2110%5D%5B142:1:142%5D%5B0:1:0%5D",
      "tcdc_spread": "https://psl.noaa.gov/thredds/dodsC/Datasets/20thC_ReanV3/spreads/miscSI/tcdc.eatm.1822.nc.ascii?tcdc%5B2106:1:2110%5D%5B142:1:142%5D%5B0:1:0%5D",
      "uwnd_mean": "https://psl.noaa.gov/thredds/dodsC/Datasets/20thC_ReanV3/10mSI/uwnd.10m.1822.nc.ascii?uwnd%5B2106:1:2110%5D%5B142:1:142%5D%5B0:1:0%5D",
      "uwnd_spread": "https://psl.noaa.gov/thredds/dodsC/Datasets/20thC_ReanV3/spreads/10mSI/uwnd.10m.1822.nc.ascii?uwnd%5B2106:1:2110%5D%5B142:1:142%5D%5B0:1:0%5D",
      "vwnd_mean": "https://psl.noaa.gov/thredds/dodsC/Datasets/20thC_ReanV3/10mSI/vwnd.10m.1822.nc.ascii?vwnd%5B2106:1:2110%5D%5B142:1:142%5D%5B0:1:0%5D",
      "vwnd_spread": "https://psl.noaa.gov/thredds/dodsC/Datasets/20thC_ReanV3/spreads/10mSI/vwnd.10m.1822.nc.ascii?vwnd%5B2106:1:2110%5D%5B142:1:142%5D%5B0:1:0%5D",
      "air_mean": "https://psl.noaa.gov/thredds/dodsC/Datasets/20thC_ReanV3/2mSI/air.2m.1822.nc.ascii?air%5B2106:1:2110%5D%5B142:1:142%5D%5B0:1:0%5D",
      "air_spread": "https://psl.noaa.gov/thredds/dodsC/Datasets/20thC_ReanV3/spreads/2mSI/air.2m.1822.nc.ascii?air%5B2106:1:2110%5D%5B142:1:142%5D%5B0:1:0%5D"
    },
    "limit": "A 1-degree pressure-assimilating ensemble is regional context, not an observation at Hampstead; the cloud-cover spread is comparable to its mean."
  },
  "instrumental": {
    "dataset": "Met Office Hadley Centre Central England Temperature, daily means",
    "source_url": "https://www.metoffice.gov.uk/hadobs/hadcet/data/meantemp_daily_totals.txt",
    "daily_mean_c": {
      "1822-09-17": 14.5,
      "1822-09-18": 12.9,
      "1822-09-19": 12.4,
      "1822-09-20": 11.6,
      "1822-09-21": 11.6,
      "1822-09-22": 12.4,
      "1822-09-23": 12.6,
      "1822-09-26": 9.5
    },
    "note": "CET is a composite over a Central England triangle, not a London station; afternoon maxima typically run a few degrees above the daily mean. The 11.6 C daily mean on 1822-09-21 sat in a mild spell that collapsed toward 9.5 C by 1822-09-26."
  },
  "written_record": {
    "observer": "Luke Howard, The Climate of London, 2nd edition, 3 vols, London: Harvey and Darton, 1833",
    "coverage": "Vol. III, Meteorological Observations made at Tottenham and at Stratford, near London, 1819-1827; Table CXCVI (September 1822), p. 90, notes pp. 90-91",
    "entry_1822_09_21": {
      "wind": "NE",
      "barometer_inches": [
        29.87,
        29.8
      ],
      "note": "Howard's note covering the 17th through the 21st reads: Fine."
    },
    "month_wind_tally_sept_1822": {
      "N": 3,
      "NE": 9,
      "E": 4,
      "SE": 1,
      "SW": 5,
      "W": 1,
      "NW": 7
    },
    "caveats": "Station attribution (Stratford register with parallel Tottenham figures) is inferred, not labelled per table. The day-21 wind letter was transcribed independently twice from archive.org scans (b29350529_0003, b29350529_0006), both reading NE, but comes from OCR row-counting of the daily table; verify against the page image before archival citation. The prose note and monthly wind totals are solid.",
    "constable_letters": {
      "source": "C.R. Leslie, Memoirs of the Life of John Constable, 2nd edition, London, 1845",
      "skying_letter": "I have done a good deal of skying, for I am determined to conquer all difficulties, and that among the rest. (To John Fisher, Hampstead, 23 October 1821, pp. 91-93)",
      "fifty_studies": "I have made about fifty careful studies of skies, tolerably large to be careful. (To John Fisher, Hampstead, 7 October 1822, p. 101)",
      "leslie_on_versos": "They are painted in oil, on large sheets of thick paper, and all dated, with the time of day, the direction of the wind, and other memoranda on their backs. (Leslie, p. 102)"
    },
    "scholarship": "John Thornes, Constable's Clouds, The Burlington Magazine 121 (1979), pp. 697-704: the weather notes on the 1821-22 studies are accurate enough that nine undated studies were assigned years from historical weather records alone. This painting is catalogued in Thornes, John Constable's Skies (1999) as no. 52, plate 123, per the YCBA bibliography."
  }
}