V8

Question 1

Radiation balance – diurnal course:

Answer 1

Question 2

Effects of longwave radiation – “beer garden”-microclimate:

Answer 2

• reduction of outgoing longwave radiation by absorption in the canopy
• back radiation from canopy and stems ⇒ less evening cooling, more comfortable microclimate

Question 3

Strahlungsbilanz - verschiedene Landnutzungsarten:

Answer 3

Question 4

Energy balance:

Answer 4

Question 5

Energy balance:

Answer 5

Question 6

Energy balance:

Answer 6

Question 7

Energy balance:

Answer 7

Question 8

Albedo:

Answer 8

• Rückstrahlungsvermögen von nicht selbstleuchtenden, diffus reflektierenden Oberflächen (z. B. Schnee, Eis)

Question 9

Spatial approaches:

Answer 9

• remote sensing

Question 10

Climate-vegetation interactions:

Carbon flux

Answer 10

Question 11

Climate-vegetation interactions:

Air temperature

Answer 11

Question 12

Climate-vegetation interactions:

Air temperature profiles in plant stands

Answer 12

Question 13

Climate-vegetation interactions:

Air temperature profiles in plant stands

Answer 13

Question 14

Climate-vegetation interactions:

Air temperature

Answer 14

• annual T-amplitude

Question 15

Climate-vegetation interactions:

Air temperature profiles in plant stands

Answer 15

Question 16

Climate-vegetation interactions:

Air temperature profiles in plant stands

Answer 16

Question 17

Climate-vegetation interactions:

Air temperature in plant stands

Answer 17

Question 18

Climate-vegetation interactions:

High-frequence variability

Answer 18

Question 19

Climate-vegetation interactions:

Small-scale variability of temperature

Answer 19

• On what factors does horizontal T variability depend (e.g., in a field)?
  
  • exposition
  • radiation balance
  • plant cover
  • water ⇒ evapotranspiration

variability of ET can reach 20% in a field

Question 20

Climate-vegetation interactions:

Temperature extremes: frost

Answer 20

• Frost: T2m <= 0°C
  
  • late frost (in spring: damages e.g. in fruit / wine / horticulture)
  • early frost (in autumn: threat to crops, e.g. potatoes, sugar beets)
  • night frost (night radiation, cloudless, wind protected)
• snow cover often can be good frost protection

Question 21

Climate-vegetation interactions:

Counter measures

Answer 21

• Frost irrigation for crops (especially fruit blossoming) in spring
• from +0.5°C continuous irrigation ⇒ thin layer of ice (solidification heat): T not significantly below freezing point over a longer period of time.
• only at rH > 80% and vwind < 2 m/s, otherwise evaporative cooling!
• no interruption of irrigation until T > 0°C
• high water input (up to 40000 L h-1 ha-1 water), soaking, leaching

Question 22

Vorhersage von Frost:

Answer 22

• Indikatoren für Frost in den nächsten paar Tagen in den kritischen Phasen:
  
  • wolkenlos
  • Temperaturinversionslagen
  • geringe Windgeschwindigkeiten (< 2 m/s)
  • stabile Hochdrucklage
• Indikator für Spätfrost in der anstehenden Saison: SOI im Herbst immer negativ oder stark fallend

Question 23

Other protective measures:

Answer 23

Question 24

Other protective measures:

Answer 24

Question 25

***Kaltlufteinbrüche*** ***(katabatische Fallwinde: zB Mistral, Bora):***

Answer 25

Question 26

***Damage to plants due to temperature variations:***

Answer 26

* Frost: volume expansion within the plant cells, rather: desiccation of the cells. * Physiological drought and desiccation: in spring still frozen soil, conifers already have strong transpiration * Heat: increased water demand due to increased assimilation, thickening of cell sap, desiccation (despite sufficient water supply in soil and air) * damage by scorching (especially cereals in the ripening phase): if the T is too high ⇒ sugars are immediately converted into starch ⇒ grains stop growing ⇒ e.g. 3 subsequent days with T \> 30°C • average cell death at 50 - 60°C

Question 27

***Relative humidity:***

Answer 27

Question 28

***Relative humidity:***

Answer 28

Question 29

***Humidity and CO 2:***

Answer 29

Question 30

***Wind:***

Answer 30

Question 31

***Vertical wind profile:***

Answer 31

Question 32

***Excursus: Nature-based solutions against wind extremes***

Answer 32

Question 33

***Windschutz:***

Answer 33

Question 34

***Wind protection:***

Answer 34

Question 35

***Combined effects of a wind protection by vegetation:***

Answer 35

Question 36

***Nature-based solutions against wind extremes:***

Answer 36

* often multiple rows of trees or shrubs perpendicular to the main wind direction * range proportional to height * dense shelters (walls, rows of houses, forests): strong reduction of wind speed, relatively short range, gustiness * mainly coastal areas, lowlands, moors, high plateaus of low mountain ranges (e.g. sensitive vegetable crops in the Rhone Valley / Mistral)