{
 "slug": "van-breen-frozen-amstel-1611",
 "object": {
  "holder": "National Gallery of Art, Washington",
  "accession": "2010.20.1",
  "artist": "Adam van Breen",
  "title": "Skating on the Frozen Amstel River",
  "date": "1611",
  "medium": "oil on panel",
  "dimensions_cm": "44.3 × 66.5",
  "inscription": "on gable of manor house: 16011",
  "credit": "The Lee and Juliet Folger Fund, in honor of Arthur K. Wheelock, Jr.",
  "painted_day": null,
  "painted_day_reason": "no_document_links_the_scene_to_a_day_or_a_particular_winter",
  "date_basis": "The gable inscription “16011”, read as 1611 by the NGA catalogue. A signature date dates the making of the panel, not the winter shown."
 },
 "windows": {
  "dated_year": "Calendar year 1611 touches two winters: November 1610–March 1611 (KNMI row 1611) and the winter that began in November 1611 (row 1612).",
  "context": "Winters 1594–95 to 1649–50 for the strip; half-centuries 1551–1600, 1601–1650 and 1651–1700 for the frequency test."
 },
 "knmi": {
  "target": {
   "year": 1611,
   "winter": "1610–11",
   "category": 6,
   "definition": "Cold",
   "verbatim": "1611,     6,     5,     14,     162,     88"
  },
  "following": {
   "year": 1612,
   "winter": "1611–12",
   "category": 6,
   "definition": "Cold"
  },
  "run": {
   "first": "1609–10",
   "last": "1611–12",
   "winters": 3,
   "category_floor": 6
  },
  "last_very_severe": {
   "winter": "1607–08",
   "category": 8
  },
  "next_severe": {
   "winter": "1617–18",
   "category": 7
  },
  "van_goyen": {
   "year": 1646,
   "winter": "1645–46",
   "category": 7,
   "definition": "Severe",
   "following_winter": "1646–47",
   "following_category": 6
  },
  "periods": [
   {
    "start": 1551,
    "end": 1600,
    "basis": "documentary",
    "winters": 50,
    "severe_or_harsher": 11,
    "cold": 15,
    "normal": 17,
    "fairly_mild": 5,
    "mild_or_milder": 2,
    "mean_category": 5.62,
    "severe_years": [
     "1553–54",
     "1556–57",
     "1560–61",
     "1564–65",
     "1568–69",
     "1572–73",
     "1580–81",
     "1585–86",
     "1589–90",
     "1594–95",
     "1599–00"
    ]
   },
   {
    "start": 1601,
    "end": 1650,
    "basis": "documentary",
    "winters": 50,
    "severe_or_harsher": 9,
    "cold": 16,
    "normal": 14,
    "fairly_mild": 11,
    "mild_or_milder": 0,
    "mean_category": 5.5,
    "severe_years": [
     "1600–01",
     "1607–08",
     "1617–18",
     "1619–20",
     "1620–21",
     "1623–24",
     "1634–35",
     "1645–46",
     "1648–49"
    ]
   },
   {
    "start": 1651,
    "end": 1700,
    "basis": "documentary",
    "winters": 50,
    "severe_or_harsher": 16,
    "cold": 13,
    "normal": 12,
    "fairly_mild": 5,
    "mild_or_milder": 4,
    "mean_category": 5.72,
    "severe_years": [
     "1654–55",
     "1657–58",
     "1659–60",
     "1662–63",
     "1666–67",
     "1669–70",
     "1671–72",
     "1676–77",
     "1678–79",
     "1680–81",
     "1683–84",
     "1690–91",
     "1691–92",
     "1694–95",
     "1696–97",
     "1697–98"
    ]
   },
   {
    "start": 1707,
    "end": 1990,
    "basis": "instrumental (De Bilt frost index)",
    "winters": 284,
    "severe_or_harsher": 44,
    "cold": 62,
    "normal": 73,
    "fairly_mild": 60,
    "mild_or_milder": 45,
    "mean_category": 5,
    "severe_years": [
     "1708–09",
     "1715–16",
     "1725–26",
     "1728–29",
     "1739–40",
     "1754–55",
     "1756–57",
     "1759–60",
     "1762–63",
     "1766–67",
     "1775–76",
     "1783–84",
     "1784–85",
     "1788–89",
     "1794–95",
     "1798–99",
     "1799–00",
     "1802–03",
     "1804–05",
     "1813–14",
     "1819–20",
     "1822–23",
     "1828–29",
     "1829–30",
     "1837–38",
     "1840–41",
     "1844–45",
     "1846–47",
     "1847–48",
     "1854–55",
     "1864–65",
     "1870–71",
     "1879–80",
     "1890–91",
     "1894–95",
     "1916–17",
     "1928–29",
     "1939–40",
     "1941–42",
     "1946–47",
     "1955–56",
     "1962–63",
     "1978–79",
     "1984–85"
    ]
   },
   {
    "start": 1951,
    "end": 2000,
    "basis": "instrumental (De Bilt frost index)",
    "winters": 50,
    "severe_or_harsher": 5,
    "cold": 9,
    "normal": 8,
    "fairly_mild": 12,
    "mild_or_milder": 16,
    "mean_category": 4.34,
    "severe_years": [
     "1955–56",
     "1962–63",
     "1978–79",
     "1984–85",
     "1995–96"
    ]
   }
  ],
  "reference": [
   {
    "category": 1,
    "definition": "Extremely mild",
    "printed_percent": 1.0,
    "file_percent": 0.7,
    "file_count": 2
   },
   {
    "category": 2,
    "definition": "Very mild",
    "printed_percent": 3.8,
    "file_percent": 3.9,
    "file_count": 11
   },
   {
    "category": 3,
    "definition": "Mild",
    "printed_percent": 11.1,
    "file_percent": 11.3,
    "file_count": 32
   },
   {
    "category": 4,
    "definition": "Fairly mild",
    "printed_percent": 21.0,
    "file_percent": 21.1,
    "file_count": 60
   },
   {
    "category": 5,
    "definition": "Normal",
    "printed_percent": 26.2,
    "file_percent": 25.7,
    "file_count": 73
   },
   {
    "category": 6,
    "definition": "Cold",
    "printed_percent": 21.0,
    "file_percent": 21.8,
    "file_count": 62
   },
   {
    "category": 7,
    "definition": "Severe",
    "printed_percent": 11.1,
    "file_percent": 10.9,
    "file_count": 31
   },
   {
    "category": 8,
    "definition": "Very severe",
    "printed_percent": 3.8,
    "file_percent": 3.9,
    "file_count": 11
   },
   {
    "category": 9,
    "definition": "Extremely severe",
    "printed_percent": 1.0,
    "file_percent": 0.7,
    "file_count": 2
   }
  ],
  "strip": [
   {
    "year": 1595,
    "winter": "1594–95",
    "category": 8,
    "definition": "Very severe",
    "verbatim": "1595,     8,     5,    -16,     160,     75"
   },
   {
    "year": 1596,
    "winter": "1595–96",
    "category": 5,
    "definition": "Normal",
    "verbatim": "1596,     5,     4,     20,     156,     88"
   },
   {
    "year": 1597,
    "winter": "1596–97",
    "category": 5,
    "definition": "Normal",
    "verbatim": "1597,     5,     3,     20,     153,     86"
   },
   {
    "year": 1598,
    "winter": "1597–98",
    "category": 6,
    "definition": "Cold",
    "verbatim": "1598,     6,     5,     16,     163,     89"
   },
   {
    "year": 1599,
    "winter": "1598–99",
    "category": 6,
    "definition": "Cold",
    "verbatim": "1599,     6,     6,     12,     167,     90"
   },
   {
    "year": 1600,
    "winter": "1599–00",
    "category": 7,
    "definition": "Severe",
    "verbatim": "1600,     7,     3,      1,     151,     77"
   },
   {
    "year": 1601,
    "winter": "1600–01",
    "category": 7,
    "definition": "Severe",
    "verbatim": "1601,     7,     4,    -14,     155,     74"
   },
   {
    "year": 1602,
    "winter": "1601–02",
    "category": 6,
    "definition": "Cold",
    "verbatim": "1602,     6,     5,     12,     163,     88"
   },
   {
    "year": 1603,
    "winter": "1602–03",
    "category": 6,
    "definition": "Cold",
    "verbatim": "1603,     6,     6,      8,     166,     88"
   },
   {
    "year": 1604,
    "winter": "1603–04",
    "category": 5,
    "definition": "Normal",
    "verbatim": "1604,     5,     6,     20,     168,     94"
   },
   {
    "year": 1605,
    "winter": "1604–05",
    "category": 4,
    "definition": "Fairly mild",
    "verbatim": "1605,     4,     5,     29,     160,     93"
   },
   {
    "year": 1606,
    "winter": "1605–06",
    "category": 5,
    "definition": "Normal",
    "verbatim": "1606,     5,     4,     23,     155,     89"
   },
   {
    "year": 1607,
    "winter": "1606–07",
    "category": 4,
    "definition": "Fairly mild",
    "verbatim": "1607,     4,     5,     38,     162,     98"
   },
   {
    "year": 1608,
    "winter": "1607–08",
    "category": 8,
    "definition": "Very severe",
    "verbatim": "1608,     8,     4,    -20,     159,     73"
   },
   {
    "year": 1609,
    "winter": "1608–09",
    "category": 4,
    "definition": "Fairly mild",
    "verbatim": "1609,     4,     5,     38,     160,     97"
   },
   {
    "year": 1610,
    "winter": "1609–10",
    "category": 6,
    "definition": "Cold",
    "verbatim": "1610,     6,     5,     14,     164,     89"
   },
   {
    "year": 1611,
    "winter": "1610–11",
    "category": 6,
    "definition": "Cold",
    "verbatim": "1611,     6,     5,     14,     162,     88"
   },
   {
    "year": 1612,
    "winter": "1611–12",
    "category": 6,
    "definition": "Cold",
    "verbatim": "1612,     6,     5,      7,     164,     86"
   },
   {
    "year": 1613,
    "winter": "1612–13",
    "category": 4,
    "definition": "Fairly mild",
    "verbatim": "1613,     4,     5,     30,     161,     94"
   },
   {
    "year": 1614,
    "winter": "1613–14",
    "category": 6,
    "definition": "Cold",
    "verbatim": "1614,     6,     3,     12,     150,     81"
   },
   {
    "year": 1615,
    "winter": "1614–15",
    "category": 6,
    "definition": "Cold",
    "verbatim": "1615,     6,     6,     12,     169,     91"
   },
   {
    "year": 1616,
    "winter": "1615–16",
    "category": 6,
    "definition": "Cold",
    "verbatim": "1616,     6,     7,     11,     173,     93"
   },
   {
    "year": 1617,
    "winter": "1616–17",
    "category": 4,
    "definition": "Fairly mild",
    "verbatim": "1617,     4,     3,     38,     152,     93"
   },
   {
    "year": 1618,
    "winter": "1617–18",
    "category": 7,
    "definition": "Severe",
    "verbatim": "1618,     7,     3,      1,     150,     77"
   },
   {
    "year": 1619,
    "winter": "1618–19",
    "category": 5,
    "definition": "Normal",
    "verbatim": "1619,     5,     5,     26,     161,     92"
   },
   {
    "year": 1620,
    "winter": "1619–20",
    "category": 7,
    "definition": "Severe",
    "verbatim": "1620,     7,     5,      2,     160,     82"
   },
   {
    "year": 1621,
    "winter": "1620–21",
    "category": 8,
    "definition": "Very severe",
    "verbatim": "1621,     8,     2,    -18,     145,     67"
   },
   {
    "year": 1622,
    "winter": "1621–22",
    "category": 6,
    "definition": "Cold",
    "verbatim": "1622,     6,     4,     12,     158,     85"
   },
   {
    "year": 1623,
    "winter": "1622–23",
    "category": 5,
    "definition": "Normal",
    "verbatim": "1623,     5,     6,     18,     166,     92"
   },
   {
    "year": 1624,
    "winter": "1623–24",
    "category": 7,
    "definition": "Severe",
    "verbatim": "1624,     7,     7,      2,     172,     88"
   },
   {
    "year": 1625,
    "winter": "1624–25",
    "category": 5,
    "definition": "Normal",
    "verbatim": "1625,     5,     4,     18,     158,     87"
   },
   {
    "year": 1626,
    "winter": "1625–26",
    "category": 5,
    "definition": "Normal",
    "verbatim": "1626,     5,     4,     23,     159,     90"
   },
   {
    "year": 1627,
    "winter": "1626–27",
    "category": 6,
    "definition": "Cold",
    "verbatim": "1627,     6,     3,     15,     148,     82"
   },
   {
    "year": 1628,
    "winter": "1627–28",
    "category": 5,
    "definition": "Normal",
    "verbatim": "1628,     5,     1,     19,     140,     79"
   },
   {
    "year": 1629,
    "winter": "1628–29",
    "category": 4,
    "definition": "Fairly mild",
    "verbatim": "1629,     4,     7,     29,     173,    100"
   },
   {
    "year": 1630,
    "winter": "1629–30",
    "category": 4,
    "definition": "Fairly mild",
    "verbatim": "1630,     4,     6,     36,     169,    101"
   },
   {
    "year": 1631,
    "winter": "1630–31",
    "category": 5,
    "definition": "Normal",
    "verbatim": "1631,     5,     7,     24,     173,     98"
   },
   {
    "year": 1632,
    "winter": "1631–32",
    "category": 4,
    "definition": "Fairly mild",
    "verbatim": "1632,     4,     4,     36,     158,     95"
   },
   {
    "year": 1633,
    "winter": "1632–33",
    "category": 4,
    "definition": "Fairly mild",
    "verbatim": "1633,     4,     4,     30,     154,     91"
   },
   {
    "year": 1634,
    "winter": "1633–34",
    "category": 6,
    "definition": "Cold",
    "verbatim": "1634,     6,     5,      5,     160,     84"
   },
   {
    "year": 1635,
    "winter": "1634–35",
    "category": 7,
    "definition": "Severe",
    "verbatim": "1635,     7,     6,     -2,     167,     84"
   },
   {
    "year": 1636,
    "winter": "1635–36",
    "category": 5,
    "definition": "Normal",
    "verbatim": "1636,     5,     7,     21,     172,     96"
   },
   {
    "year": 1637,
    "winter": "1636–37",
    "category": 5,
    "definition": "Normal",
    "verbatim": "1637,     5,     7,     27,     175,    100"
   },
   {
    "year": 1638,
    "winter": "1637–38",
    "category": 6,
    "definition": "Cold",
    "verbatim": "1638,     6,     6,     10,     169,     90"
   },
   {
    "year": 1639,
    "winter": "1638–39",
    "category": 5,
    "definition": "Normal",
    "verbatim": "1639,     5,     5,     28,     162,     94"
   },
   {
    "year": 1640,
    "winter": "1639–40",
    "category": 5,
    "definition": "Normal",
    "verbatim": "1640,     5,     5,     17,     162,     89"
   },
   {
    "year": 1641,
    "winter": "1640–41",
    "category": 6,
    "definition": "Cold",
    "verbatim": "1641,     6,     5,     15,     161,     88"
   },
   {
    "year": 1642,
    "winter": "1641–42",
    "category": 4,
    "definition": "Fairly mild",
    "verbatim": "1642,     4,     4,     28,     158,     92"
   },
   {
    "year": 1643,
    "winter": "1642–43",
    "category": 5,
    "definition": "Normal",
    "verbatim": "1643,     5,     5,     26,     164,     94"
   },
   {
    "year": 1644,
    "winter": "1643–44",
    "category": 6,
    "definition": "Cold",
    "verbatim": "1644,     6,     6,     12,     169,     91"
   },
   {
    "year": 1645,
    "winter": "1644–45",
    "category": 6,
    "definition": "Cold",
    "verbatim": "1645,     6,     6,     16,     169,     92"
   },
   {
    "year": 1646,
    "winter": "1645–46",
    "category": 7,
    "definition": "Severe",
    "verbatim": "1646,     7,     7,      1,     171,     87"
   },
   {
    "year": 1647,
    "winter": "1646–47",
    "category": 6,
    "definition": "Cold",
    "verbatim": "1647,     6,     5,     12,     164,     88"
   },
   {
    "year": 1648,
    "winter": "1647–48",
    "category": 4,
    "definition": "Fairly mild",
    "verbatim": "1648,     4,     4,     35,     155,     93"
   },
   {
    "year": 1649,
    "winter": "1648–49",
    "category": 7,
    "definition": "Severe",
    "verbatim": "1649,     7,     3,      3,     152,     79"
   },
   {
    "year": 1650,
    "winter": "1649–50",
    "category": 5,
    "definition": "Normal",
    "verbatim": "1650,     5,     4,     26,     154,     89"
   }
  ]
 },
 "fabricius": {
  "observer": "David Fabricius, Calendarium Historicum",
  "place": {
   "name": "Osteel, East Frisia",
   "lat": 53.5336832,
   "lon": 7.2642003,
   "distance_to_amsterdam_km": 205,
   "distance_basis": "Great-circle distance between OpenStreetMap village and city points; approximate."
  },
  "months": [
   {
    "month": "October 1610",
    "frost_days": 4,
    "mean_1593_1612": 3.3,
    "mean_recomputed": 3.25
   },
   {
    "month": "November 1610",
    "frost_days": 5,
    "mean_1593_1612": 6.5,
    "mean_recomputed": 6.55
   },
   {
    "month": "December 1610",
    "frost_days": 14,
    "mean_1593_1612": 14.4,
    "mean_recomputed": 14.35
   },
   {
    "month": "January 1611",
    "frost_days": 22,
    "mean_1593_1612": 13.3,
    "mean_recomputed": 13.3
   },
   {
    "month": "February 1611",
    "frost_days": 6,
    "mean_1593_1612": 15.6,
    "mean_recomputed": 15.6
   },
   {
    "month": "March 1611",
    "frost_days": 2,
    "mean_1593_1612": 10.8,
    "mean_recomputed": 10.8
   },
   {
    "month": "April 1611",
    "frost_days": 5,
    "mean_1593_1612": 3.3,
    "mean_recomputed": 3.3
   }
  ],
  "winter": {
   "winter": "1610–11",
   "frost_days": 58,
   "pilgram": "1611 kalter Winter",
   "easton": "tiède",
   "knmi_category": 6,
   "knmi_definition": "Cold",
   "rank": 12,
   "tied_with": [
    "1601–02"
   ],
   "of": 19
  },
  "following": {
   "winter": "1611–12",
   "frost_days": 80,
   "pilgram": "1612 kalter Winter",
   "easton": "normal pl. froid",
   "knmi_category": 6,
   "knmi_definition": "Cold",
   "rank": 5,
   "tied_with": [],
   "of": 19
  },
  "harsh_1608": {
   "winter": "1607–08",
   "frost_days": 96,
   "pilgram": "1608 ungemein kalter Winter",
   "easton": "Grand Hiver",
   "knmi_category": 8,
   "knmi_definition": "Very severe",
   "rank": 2,
   "tied_with": [],
   "of": 19
  },
  "winter_range": {
   "minimum": 35,
   "maximum": 99,
   "median": 69
  },
  "january": {
   "frost_days": 22,
   "mean_1593_1612": 13.3,
   "rank": 2,
   "tied_with": [
    1599
   ],
   "of": 20
  },
  "february": {
   "frost_days": 6,
   "mean_1593_1612": 15.6,
   "fewer_than": 17,
   "of": 20
  },
  "spell": {
   "start": "23 XII 1610",
   "end": "26 I 1611",
   "interruptions": "3 I and 12–14 I 1611 (rain)",
   "check": "Dec 1610: 1–5 and 23–31 = 14 days; Jan 1611: 1–26 minus 3 and 12–14 = 22 days; Feb 1611: 15–20 = 6 days; Mar 1611: 15–16 = 2 days. These equal the Table 5 c cells."
  },
  "narrative": [
   {
    "month": "1610 XI (end)",
    "text": "Nur vom 11. bis 13. und 29. bis 30. herrschte Frost,"
   },
   {
    "month": "1610 XII",
    "text": "der vom 1. bis 5. bei nordöstlichen Winden fortdauerte. Beides wiederholte sich mit ztw. Schneefall vom 23. ab. Vom 6. bis 22. war es — meist bei Winden zwischen Südwest und West, z. T. zwischen Süd und Nord — trübe mit vereinzelten Schnee-, Graupel- oder Regenfällen."
   },
   {
    "month": "1611 I",
    "text": "Bei wechselnden, ztw. östlichen Winden vom 1. bis 10., südwest- bis westlichen vom 11. bis 17. und östlichen vom 18. bis 26. wurde das seit dem 23. XII. andauernde Frostwetter nur am 3. und 12. bis 14. I. bei Regen unterbrochen; sonst fiel mehrfach Schnee. Vom 27. I. ab herrschte weiches Wetter, es setzte"
   },
   {
    "month": "1611 II",
    "text": "sich bis zum 14. II. bei Winden zwischen Süd und West fort; dabei herrschte trübes und feuchtes Wetter. Mit Ostwinden (14. bis 19.) schaltete sich dann eine Frostperiode (15. bis 20.) dazwischen, während welcher anfangs Schnee fiel. Ihr folgte bis 6. III. bei Winden zwischen Süd und West (20. bis 25. II.) und späteren"
   },
   {
    "month": "1611 III",
    "text": "Ostwinden (26. II. bis 6. III.) „wasserkaltes“ Wetter, in dem vereinzelt Schnee fiel. Vom 7. bis Ende des März herrschte trübes Wetter mit vereinzeltem Sonnenschein und Regen, sowie Frost (15. und 16.)."
   }
  ],
  "winters": [
   {
    "winter": "1593–94",
    "frost_days": 47,
    "pilgram": "1594 sehr kalter Winter (1595?)",
    "easton": "normal",
    "knmi_category": 5,
    "knmi_definition": "Normal"
   },
   {
    "winter": "1594–95",
    "frost_days": 88,
    "pilgram": null,
    "easton": "très rigoureux",
    "knmi_category": 8,
    "knmi_definition": "Very severe"
   },
   {
    "winter": "1595–96",
    "frost_days": 53,
    "pilgram": null,
    "easton": "tiède",
    "knmi_category": 5,
    "knmi_definition": "Normal"
   },
   {
    "winter": "1596–97",
    "frost_days": 60,
    "pilgram": null,
    "easton": "normal",
    "knmi_category": 5,
    "knmi_definition": "Normal"
   },
   {
    "winter": "1597–98",
    "frost_days": 72,
    "pilgram": null,
    "easton": "normal pl. froid",
    "knmi_category": 6,
    "knmi_definition": "Cold"
   },
   {
    "winter": "1598–99",
    "frost_days": 69,
    "pilgram": "1599 kalter Winter (1600?)",
    "easton": "normal",
    "knmi_category": 6,
    "knmi_definition": "Cold"
   },
   {
    "winter": "1599–00",
    "frost_days": 86,
    "pilgram": null,
    "easton": "froid",
    "knmi_category": 7,
    "knmi_definition": "Severe"
   },
   {
    "winter": "1600–01",
    "frost_days": 99,
    "pilgram": "1601 große Kälte",
    "easton": "normal (!!)",
    "knmi_category": 7,
    "knmi_definition": "Severe"
   },
   {
    "winter": "1601–02",
    "frost_days": 58,
    "pilgram": null,
    "easton": "tiède",
    "knmi_category": 6,
    "knmi_definition": "Cold"
   },
   {
    "winter": "1602–03",
    "frost_days": 79,
    "pilgram": "1603 große Kälte",
    "easton": "froid",
    "knmi_category": 6,
    "knmi_definition": "Cold"
   },
   {
    "winter": "1603–04",
    "frost_days": 75,
    "pilgram": "1604 langer und strenger Winter",
    "easton": "tiède",
    "knmi_category": 5,
    "knmi_definition": "Normal"
   },
   {
    "winter": "1604–05",
    "frost_days": 47,
    "pilgram": null,
    "easton": "normal",
    "knmi_category": 4,
    "knmi_definition": "Fairly mild"
   },
   {
    "winter": "1605–06",
    "frost_days": 55,
    "pilgram": "1606 kalter Winter",
    "easton": "froid",
    "knmi_category": 5,
    "knmi_definition": "Normal"
   },
   {
    "winter": "1606–07",
    "frost_days": 35,
    "pilgram": null,
    "easton": "tiède",
    "knmi_category": 4,
    "knmi_definition": "Fairly mild"
   },
   {
    "winter": "1607–08",
    "frost_days": 96,
    "pilgram": "1608 ungemein kalter Winter",
    "easton": "Grand Hiver",
    "knmi_category": 8,
    "knmi_definition": "Very severe"
   },
   {
    "winter": "1608–09",
    "frost_days": 38,
    "pilgram": null,
    "easton": "doux",
    "knmi_category": 4,
    "knmi_definition": "Fairly mild"
   },
   {
    "winter": "1609–10",
    "frost_days": 70,
    "pilgram": null,
    "easton": "normal pl. froid",
    "knmi_category": 6,
    "knmi_definition": "Cold"
   },
   {
    "winter": "1610–11",
    "frost_days": 58,
    "pilgram": "1611 kalter Winter",
    "easton": "tiède",
    "knmi_category": 6,
    "knmi_definition": "Cold"
   },
   {
    "winter": "1611–12",
    "frost_days": 80,
    "pilgram": "1612 kalter Winter",
    "easton": "normal pl. froid",
    "knmi_category": 6,
    "knmi_definition": "Cold"
   }
  ],
  "checks": {
   "rows_matching_printed_total": 19,
   "rows_checked": 20,
   "mismatches": [
    {
     "year": 1594,
     "months_sum": 71,
     "printed_total": 72
    }
   ],
   "winter_totals_reproduced": 19,
   "note": "Every printed winter total equals the October–May cells of the monthly table. The 1594 row sums to 71 against a printed 72; Lenke’s text gives a 67.3-day annual mean, consistent with 71."
  },
  "independence": "The KNMI reconstruction lists Fabricius’s East Frisian frost-day counts among the series that contributed to its 1591–1613 estimates; this is not an independent check on the 1610–11 category."
 },
 "definitions": {
  "category": "KNMI C_win: a nine-step documentary classification of the November–March season for the Low Countries, from 1 (extremely mild) to 9 (extremely severe). It is compiled evidence, not an observation at Amsterdam.",
  "labels": "Category names follow Table 2 of van Engelen, Buisman and IJnsen (2001): 6 is “Cold”, 7 “Severe”, 8 “Very severe”.",
  "reference": "The classification divides the 284 instrumental winters of 1707–1990 symmetrically around 5; its printed frequencies are reproduced by the file’s own 1707–1990 rows. The reference period itself lies largely within the Little Ice Age.",
  "year": "Row Y is the winter ending in Y: the chapter’s “1248–1249 WINTER: FAIRLY MILD (4)” is stored as 4 in row 1249.",
  "frost_days": "Fabricius frost days are Lenke’s counts from a written diary, including days inferred within frost spells; they are not thermometer readings.",
  "calendar": "The Lenke pages consulted do not state whether diary dates were converted between calendars. A ten-day Julian offset would move the 23 December–26 January spell to about 2 January–5 February."
 },
 "quotations": {
  "inscription": {
   "text": "on gable of manor house: 16011",
   "source": "nga-object",
   "attribution": "NGA object record, Inscriptions.",
   "url": "https://www.nga.gov/artworks/150754-skating-frozen-amstel-river"
  },
  "date-note": {
   "text": "there is no reason to doubt that the painting’s date is 1611",
   "source": "nga-entry",
   "attribution": "Libby (2017), note 3, on the unusual “16011”.",
   "url": "https://www.nga.gov/research/publications/online-editions/dutch-paintings-seventeenth-century-skating-frozen-amstel"
  },
  "place": {
   "text": "depicts an identifiable location on the Amstel just south of Amsterdam",
   "source": "nga-entry",
   "attribution": "Libby (2017).",
   "url": "https://www.nga.gov/research/publications/online-editions/dutch-paintings-seventeenth-century-skating-frozen-amstel"
  },
  "day": {
   "text": "on a bright, wintry day",
   "source": "nga-entry",
   "attribution": "Libby (2017), opening sentence.",
   "url": "https://www.nga.gov/research/publications/online-editions/dutch-paintings-seventeenth-century-skating-frozen-amstel"
  },
  "wind": {
   "text": "wind blows smoke from a chimney, causes flags to flutter, and fills the sails of an iceboat",
   "source": "nga-entry",
   "attribution": "Libby (2017).",
   "url": "https://www.nga.gov/research/publications/online-editions/dutch-paintings-seventeenth-century-skating-frozen-amstel"
  },
  "revision": {
   "text": "a compositional revision Van Breen made to the completed painting after the church’s spire had been added",
   "source": "nga-entry",
   "attribution": "Libby (2017), on the Zuiderkerk tower; the spire dates from 1614.",
   "url": "https://www.nga.gov/research/publications/online-editions/dutch-paintings-seventeenth-century-skating-frozen-amstel"
  },
  "severe": {
   "text": "likely in part due to a series of severe winters in the Low Countries",
   "source": "nga-entry",
   "attribution": "Libby (2017), on why skating scenes were popular in the first half of the century.",
   "url": "https://www.nga.gov/research/publications/online-editions/dutch-paintings-seventeenth-century-skating-frozen-amstel"
  },
  "orchestrated": {
   "text": "carefully orchestrated composition",
   "source": "nga-entry",
   "attribution": "Libby (2017), on the house as part of the composition.",
   "url": "https://www.nga.gov/research/publications/online-editions/dutch-paintings-seventeenth-century-skating-frozen-amstel"
  },
  "author": {
   "text": "By Alexandra Libby",
   "source": "nga-entry",
   "attribution": "NGA online edition, author line.",
   "url": "https://www.nga.gov/research/publications/online-editions/dutch-paintings-seventeenth-century-skating-frozen-amstel"
  },
  "published": {
   "text": "Published online June 30, 2017",
   "source": "nga-entry",
   "attribution": "NGA online edition, publication history.",
   "url": "https://www.nga.gov/research/publications/online-editions/dutch-paintings-seventeenth-century-skating-frozen-amstel"
  },
  "chilly": {
   "text": "amid a sequence of chilly winters in the Low Countries",
   "source": "nga-degroot",
   "attribution": "Degroot, NGA (2023), on Van Breen’s painting.",
   "url": "https://www.nga.gov/stories/articles/painting-climate-change-17th-century"
  },
  "colder": {
   "text": "winter was even colder",
   "source": "nga-degroot",
   "attribution": "Degroot, NGA (2023), on 1646, the year of Van Goyen’s NGA ice scene.",
   "url": "https://www.nga.gov/stories/articles/painting-climate-change-17th-century"
  },
  "plausible": {
   "text": "seem to recreate, with plausible detail, real-life gatherings in frigid weather",
   "source": "nga-degroot",
   "attribution": "Degroot, NGA (2023), on winter landscapes.",
   "url": "https://www.nga.gov/stories/articles/painting-climate-change-17th-century"
  },
  "goyen-date": {
   "text": "lower right on the boat, VG in monogram: VG 1646",
   "source": "nga-van-goyen",
   "attribution": "NGA object record for 2014.35.1, Inscriptions.",
   "url": "https://www.nga.gov/artworks/165221-ice-scene-near-wooden-observation-tower"
  },
  "rijks-date": {
   "text": "signature and date, on the flag of the ice-boat on the left: ‘A.v.Breen. 1611.’",
   "source": "rijksmuseum",
   "attribution": "Rijksmuseum SK-A-2510, Inscriptions / marks.",
   "url": "https://www.rijksmuseum.nl/en/collection/SK-A-2510/catalogue-entry"
  },
  "open-access": {
   "text": "This object’s media is free and in the public domain.",
   "source": "nga-object",
   "attribution": "NGA object record.",
   "url": "https://www.nga.gov/artworks/150754-skating-frozen-amstel-river"
  },
  "cc0": {
   "text": "under Creative Commons Zero (CC0)",
   "source": "nga-terms",
   "attribution": "NGA Open Access Policy.",
   "url": "https://www.nga.gov/terms-and-notices"
  },
  "frost-spell": {
   "text": "das seit dem 23. XII. andauernde Frostwetter",
   "source": "lenke-text",
   "attribution": "Lenke (1968), p. 27, summarizing Fabricius’s diary for January 1611 at Osteel.",
   "url": "https://dwdbib.dwd.de/retrosammlung/download/pdf/38758#page=27"
  },
  "osteel": {
   "text": "von 1603 bis 1613 in Osteel angestellt",
   "source": "lenke-text-method",
   "attribution": "Lenke (1968), p. 8, on where Fabricius observed.",
   "url": "https://dwdbib.dwd.de/retrosammlung/download/pdf/38758#page=8"
  },
  "earliest-series": {
   "text": "Leiden 1697 - 1698",
   "source": "knmi-page",
   "attribution": "KNMI inventory of early Dutch observations: the Senguerdius series, the earliest it lists.",
   "url": "https://www.knmi.nl/nederland-nu/klimatologie/daggegevens/antieke-waarnemingen"
  },
  "first-network": {
   "text": "Delft, Leiden, Rijnsburg 06 - 20",
   "source": "knmi-page",
   "attribution": "KNMI inventory: the first long instrumental series, 1706–1720.",
   "url": "https://www.knmi.nl/nederland-nu/klimatologie/daggegevens/antieke-waarnemingen"
  },
  "buisman-iv": {
   "text": "Vol. IV, covering the era 1575-1700",
   "source": "knmi-chapter-page",
   "attribution": "KNMI publication record for the 2001 chapter, on Buisman’s descriptive volumes.",
   "url": "https://www.knmi.nl/research/publications/a-millennium-of-weather-winds-and-water-in-the-low-countries"
  }
 },
 "receipts": {
  "nga-entry": {
   "title": "Alexandra Libby, “Skating on the Frozen Amstel River, 1611,” Dutch Paintings of the Seventeenth Century, NGA online edition (2017)",
   "url": "https://www.nga.gov/research/publications/online-editions/dutch-paintings-seventeenth-century-skating-frozen-amstel",
   "sha256": "c99c4560879c4e66db820a5a8d926bf372d5758b1d765e26e11b2d4173ffd19d",
   "retrieved_at": "2026-10-15",
   "license": "Copyright NGA; brief quotation and paraphrase",
   "locator": "Entry, technical summary and notes 3 and 5; HTML as served, fetched inside a browser session because direct requests return 403"
  },
  "nga-object": {
   "title": "National Gallery of Art, 2010.20.1: object record",
   "url": "https://www.nga.gov/artworks/150754-skating-frozen-amstel-river",
   "sha256": "eb1371e4bbb3d54e4bb5e4ce7c7a2d59264a135e4b978e2b07c7c209ec4308b7",
   "retrieved_at": "2026-10-15",
   "license": "Museum text; brief quotation",
   "locator": "Inscriptions & Marks; Open Access statement; provenance; HTML fetched inside a browser session"
  },
  "nga-terms": {
   "title": "National Gallery of Art, Open Access Policy",
   "url": "https://www.nga.gov/terms-and-notices",
   "sha256": "1f93fe7ce9cb282d15da0dc3473b69abfa47b0df8bf337d3f71896b050b0b7a0",
   "retrieved_at": "2026-10-15",
   "license": "NGA policy text; public-domain images released under CC0",
   "locator": "Open Access Policy section"
  },
  "image": {
   "title": "NGA, Skating on the Frozen Amstel River, 2010.20.1, 1600-pixel image",
   "url": "https://api.nga.gov/iiif/80b8e427-1f2c-4614-8fab-dce270763fc8/full/1600,/0/default.jpg",
   "sha256": "94b509721e8cfb809c42cb066d4842d89624fd9fc32d1fc4c56e86a01d2cbb55",
   "retrieved_at": "2026-10-15",
   "license": "CC0; Courtesy National Gallery of Art, Washington",
   "locator": "IIIF derivative of the primary image listed in NGA open data (openaccess = 1)"
  },
  "nga-degroot": {
   "title": "Dagomar Degroot, “Painting Climate Change in the 17th Century,” NGA, 10 April 2023",
   "url": "https://www.nga.gov/stories/articles/painting-climate-change-17th-century",
   "sha256": "df2c0497eef52a007afcc1a31cb374de034ede6636cf8a0228b3cbfd4c4f5371",
   "retrieved_at": "2026-10-15",
   "license": "Copyright NGA; brief quotation",
   "locator": "Paragraph on Van Breen and Van Goyen; HTML fetched inside a browser session"
  },
  "nga-van-goyen": {
   "title": "National Gallery of Art, 2014.35.1: Jan van Goyen, Ice Scene near a Wooden Observation Tower",
   "url": "https://www.nga.gov/artworks/165221-ice-scene-near-wooden-observation-tower",
   "sha256": "760909555469011717bc2f2cf6303fb628e472511d6baffe9a887cb128a9a3b8",
   "retrieved_at": "2026-10-15",
   "license": "Museum text; brief quotation",
   "locator": "Inscriptions & Marks"
  },
  "rijksmuseum": {
   "title": "Rijksmuseum, SK-A-2510: Adam van Breen, Landscape with Frozen Canal, Skaters and an Ice-Boat",
   "url": "https://www.rijksmuseum.nl/en/collection/SK-A-2510/catalogue-entry",
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   "retrieved_at": "2026-10-15",
   "license": "Museum record; brief quotation",
   "locator": "Inscriptions / marks"
  },
  "knmi-series": {
   "title": "KNMI, Nederland winter-zomer 751–2000 (data gathered by J. Buisman; described by A. F. V. van Engelen, J. Buisman and F. IJnsen)",
   "url": "https://cdn.knmi.nl/knmi/map/page/klimatologie/gegevens/daggegevens/antieke_wrn/nederland_wi_zo.zip",
   "sha256": "a5d97caee7d66ce417a41e50e763f203acb007b5774ff9c82fc55d7c2e934e03",
   "retrieved_at": "2026-10-15",
   "license": "Free use with acknowledgement of the Royal Netherlands Meteorological Institute (KNMI), per the file header",
   "locator": "nederland_wi_zo.dat, column C_win"
  },
  "knmi-page": {
   "title": "KNMI, Klimatologie: Antieke waarnemingen",
   "url": "https://www.knmi.nl/nederland-nu/klimatologie/daggegevens/antieke-waarnemingen",
   "sha256": "c6b0efdf7a398600cac08e4e80a113355ae3c1e10a7835c6e74a98e7ad604835",
   "retrieved_at": "2026-10-15",
   "license": "KNMI web page; cited",
   "locator": "Inventory of early Dutch instrumental series and the link to the winter-summer series"
  },
  "chapter": {
   "title": "van Engelen, Buisman and IJnsen, “A Millennium of Weather, Winds and Water in the Low Countries” (2001), KNMI copy",
   "url": "https://cdn.knmi.nl/system/data_center_publications/files/000/068/560/original/historyclimate.pdf?1495621264",
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   "retrieved_at": "2026-10-15",
   "license": "Copyright publisher; KNMI-hosted scan; cited and briefly quoted",
   "locator": "Table 2 and pp. 6–8 (classification, contributing series); p. 21 (winter labelling)"
  },
  "chapter-transcription": {
   "title": "Nephos transcription of Table 2 and method passages from the 2001 chapter",
   "url": "https://cdn.knmi.nl/system/data_center_publications/files/000/068/560/original/historyclimate.pdf?1495621264#page=6",
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   "retrieved_at": "2026-10-15",
   "license": "Nephos transcription; short excerpts of a copyright text",
   "locator": "Committed copy: window-engine/evidence/van-breen-frozen-amstel-1611/"
  },
  "knmi-chapter-page": {
   "title": "KNMI publication record for the 2001 chapter",
   "url": "https://www.knmi.nl/research/publications/a-millennium-of-weather-winds-and-water-in-the-low-countries",
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   "retrieved_at": "2026-10-15",
   "license": "KNMI web page; cited",
   "locator": "Abstract and PDF link"
  },
  "lenke": {
   "title": "Walter Lenke, Das Klima Ende des 16. und Anfang des 17. Jahrhunderts … David Fabricius in Ostfriesland, Berichte des Deutschen Wetterdienstes 110 (1968)",
   "url": "https://dwdbib.dwd.de/retrosammlung/download/pdf/38758",
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   "license": "Deutscher Wetterdienst retro-digitized report; figures cited, short quotation",
   "locator": "pp. 8, 10–12 (observer, frost counting); p. 27 (winter 1610–11); p. 34 (Tab. 5 c, 5 d)"
  },
  "lenke-text": {
   "title": "Lenke (1968), p. 27, text layer extracted with pdftotext 26.04.0",
   "url": "https://dwdbib.dwd.de/retrosammlung/download/pdf/38758#page=27",
   "sha256": "baabd7dd819836ca1bfa50a4a958b4a82782f29605f00b4c2bcc8d95b008a31f",
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   "license": "Extraction for quotation checks",
   "locator": "Column order in the text layer is interleaved; the quoted phrase is contiguous"
  },
  "lenke-text-method": {
   "title": "Lenke (1968), pp. 7–12, text layer extracted with pdftotext 26.04.0",
   "url": "https://dwdbib.dwd.de/retrosammlung/download/pdf/38758#page=8",
   "sha256": "36d9edcbbefebb5c771772dc635df4158b15c3ac1129a7e64bfeb1e40ac97211",
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   "license": "Extraction for quotation checks",
   "locator": "Observation places and frost counting"
  },
  "lenke-transcription": {
   "title": "Nephos transcription of Lenke’s Tab. 5 c and 5 d and the 1610–11 narrative",
   "url": "https://dwdbib.dwd.de/retrosammlung/download/pdf/38758#page=34",
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   "retrieved_at": "2026-10-15",
   "license": "Nephos transcription of published counts; short excerpts",
   "locator": "Committed copy: window-engine/evidence/van-breen-frozen-amstel-1611/"
  },
  "osteel": {
   "title": "OpenStreetMap, Osteel (village boundary point)",
   "url": "https://nominatim.openstreetmap.org/search?q=Osteel&countrycodes=de&format=json&limit=1",
   "sha256": "90159f80837d14a3cac2ac6a38f5d4d5723a097a2e41d1235a2eabe5f1d95c71",
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   "license": "ODbL 1.0; © OpenStreetMap contributors",
   "locator": "Approximate village point, not Fabricius’s house"
  },
  "amsterdam": {
   "title": "OpenStreetMap, Amsterdam (city point)",
   "url": "https://nominatim.openstreetmap.org/search?q=Amsterdam&format=json&limit=1",
   "sha256": "a586872e21d51288d421bf3b8f4cf83b1d646a9175cae061e1d3c6ad132048e2",
   "retrieved_at": "2026-10-15",
   "license": "ODbL 1.0; © OpenStreetMap contributors",
   "locator": "City point; the painted site lies on the Amstel south of the 1611 city"
  }
 }
}
