Influences of Urban Expansion on Urban Heat Island in Beijing during 1989–2010

Table 1

The thresholds of different thermodynamic levels (unit: °C).

Level	1989	2000	2010
Low	21–23.46	21–22.33	21–23.82
Submedium	23.46–24.75	22.33–23.35	23.82–25.85
Medium	24.75–25.60	23.35–24.87	25.85–27.10
Subhigh	25.60–26.87	24.87–26.85	27.10–28.91
High	26.87–30	26.85–31	28.91–32