75:
51:
60:
38:
135:). When the air is cold, bubbles of warm air are formed by the ground heating the air above it and can rise like a hot air balloon. The air is then referred to as unstable, as it's suitable for forming thermals. If there is a warm layer of air higher up, an
118:
than the surrounding air. The lighter air rises and cools due to its expansion in the lower pressure at higher altitudes. It stops rising when it has cooled to the same temperature, thus density, as the surrounding air.
90:) is a rising mass of buoyant air, a convective current in the atmosphere, that transfers heat energy vertically. Thermals are created by the uneven heating of Earth's surface from
157:
into visible droplets. When a steady wind is present, thermals and their respective cumulus clouds can align in rows oriented with wind direction, sometimes referred to as "
122:
Associated with a thermal is a downward flow surrounding the thermal column. The downward-moving exterior is caused by colder air being displaced at the top of the thermal.
74:
283:
180:(LFC), rising to great heights, condensing large quantities of water and forming convective clouds causing showers or even thunderstorms. The latter are
380:
365:
321:
370:
149:
at the top of the thermal. Cumulus clouds are formed by the rising air in a thermal as it ascends and cools, until the
375:
158:
78:
Thermal cross section with stronger lift (rising air) in darker shades of green, while red is sink (descending air).
241:
114:
warms the ground, which in turn warms the air directly above. The warm air near the surface expands, becoming less
181:
177:
31:
99:
350:
136:
50:
139:
can prevent thermals from rising high and the air is said to be stable, as mature thermals can't form.
196:
166:
59:
317:
126:
91:
263:
224:
200:
188:
162:
359:
246:
192:
143:
68:
Bubble or vortex ring thermal model (left), and column or plume thermal model (right)
256:
340:
236:
216:
173:
150:
131:
95:
37:
129:
of thermals are influenced by the properties of the lower atmosphere (the
154:
176:
energy allowing the air to rise higher. Very unstable air can reach the
17:
314:
Meteorology and Flight: Pilot's Guide to
Weather (Flying & Gliding)
251:
115:
219:, carrying dust instead of water vapor. Thermals are also seen on the
30:
This article is about the atmospheric phenomenon. For other uses, see
146:
351:
Time-lapse video of clouds caused by thermals forming and decaying
73:
36:
142:
Thermals are often indicated by the presence of visible isolated
27:
Column of rising air in the lower altitudes of Earth's atmosphere
212:
220:
111:
293:. U.S. Dept. of Transportation, FAA. 2003. pp. 9–6, 9–7
41:
Example of a thermal column between the ground and a cumulus
211:
Thermals are also seen elsewhere in the solar system. On
215:, for example, thermals are often seen in the form of
223:, typically forming hexagonal convective prisms (
8:
184:to any aircraft flying through or nearby.
284:"Glider Flying Handbook, FAA-H-8083-13A"
187:Thermals are one of the many sources of
275:
7:
25:
58:
49:
345:Thermal Structure and Behavior
172:The condensing water releases
1:
381:Severe weather and convection
341:What do thermals look like?
397:
366:Atmospheric thermodynamics
242:Atmospheric thermodynamics
29:
291:FAA government handbooks
178:level of free convection
94:, and are an example of
32:Thermal (disambiguation)
312:Bradbury, Tom (2000).
100:atmospheric convection
79:
42:
207:Thermals beyond Earth
153:in the air begins to
77:
40:
371:Aviation meteorology
347:by Wayne M. Angevine
316:. A & C Black.
376:Gliding technology
80:
43:
106:Thermals on Earth
16:(Redirected from
388:
328:
327:
309:
303:
302:
300:
298:
288:
280:
62:
53:
21:
396:
395:
391:
390:
389:
387:
386:
385:
356:
355:
337:
332:
331:
324:
311:
310:
306:
296:
294:
286:
282:
281:
277:
272:
233:
209:
108:
98:, specifically
92:solar radiation
72:
71:
70:
69:
65:
64:
63:
55:
54:
35:
28:
23:
22:
15:
12:
11:
5:
394:
392:
384:
383:
378:
373:
368:
358:
357:
354:
353:
348:
336:
335:External links
333:
330:
329:
322:
304:
274:
273:
271:
268:
267:
266:
264:Thermal energy
261:
260:
259:
249:
244:
239:
232:
229:
208:
205:
107:
104:
84:thermal column
67:
66:
57:
56:
48:
47:
46:
45:
44:
26:
24:
14:
13:
10:
9:
6:
4:
3:
2:
393:
382:
379:
377:
374:
372:
369:
367:
364:
363:
361:
352:
349:
346:
342:
339:
338:
334:
325:
323:0-7136-4226-2
319:
315:
308:
305:
292:
285:
279:
276:
269:
265:
262:
258:
255:
254:
253:
250:
248:
247:Cumulus cloud
245:
243:
240:
238:
235:
234:
230:
228:
226:
222:
218:
214:
206:
204:
202:
198:
194:
193:soaring birds
190:
185:
183:
179:
175:
170:
168:
164:
160:
159:cloud streets
156:
152:
148:
145:
140:
138:
134:
133:
128:
125:The size and
123:
120:
117:
113:
105:
103:
101:
97:
93:
89:
85:
76:
61:
52:
39:
33:
19:
344:
313:
307:
295:. Retrieved
290:
278:
257:Hang gliding
225:Bénard cells
210:
186:
171:
141:
130:
124:
121:
109:
87:
83:
81:
237:Air current
217:dust devils
174:latent heat
151:water vapor
132:troposphere
360:Categories
297:21 January
270:References
96:convection
182:dangerous
169:pilots.
137:inversion
231:See also
191:used by
155:condense
127:strength
18:Thermals
252:Gliding
197:gliders
163:soaring
144:cumulus
88:thermal
320:
167:glider
147:clouds
287:(PDF)
161:" by
116:dense
318:ISBN
299:2021
213:Mars
201:soar
195:and
189:lift
165:and
110:The
86:(or
227:).
221:sun
199:to
112:Sun
102:.
362::
343:-
289:.
203:.
82:A
326:.
301:.
34:.
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
