Microclimate for Cultural Heritage (eBook)

Cover 1
Contents 12
Foreword 6
Preface 8
Acknowledgements 9
PART I: ATMOSPHERIC PHYSICS APPLIED TO MICROCLIMATE ANALYSIS AND CONSERVATION 16
Chapter 1. Microclimate, Air and Temperature 18
1.1. The microclimate 18
1.2. Air, water vapour and perfect gases 22
1.3. Temperature 24
1.4. Mechanisms of temperature degradation 25
1.5. The temperature in a building, a room 29
1.6. The temperature in a showcase 36
1.7. Is it possible to combine people comfort, conservation needs and low cost? 39
1.8. Monitoring air temperature to study air-surface interactions and for microclimate diagnostics 45
1.9. Drawing air temperature and other isolines 53
Chapter 2. Humidity 57
2.1. Partial pressure of the water vapour 57
2.2. Derivation of the latent heats 59
2.3. Mixing ratio of dry air and water vapour 63
2.4. Monitoring mixing ratio to study air-surface interactions and for environmental diagnostics 66
2.5. Specific humidity 69
2.6. Absolute humidity 70
2.7. Relative humidity 73
2.8. The equilibrium moisture content 76
2.9. Mechanisms of humidity degradation 79
2.10. What is the best type of microclimate for conservation? 83
2.11. Keeping constant relative humidity in rooms and showcases 85
2.12. Dew point: the temperature of condensation 89
2.13. Frost point: the temperature of freezing 94
2.14. Wet bulb temperature: the temperature of evaporation 94
2.15. the psychrometric chart 98
Chapter 3. Parameters for Describing Air Masses and Vertical Motions 106
3.1. Equivalent temperature 107
3.2. Adiabatic gradient in the troposphere 108
3.3. Potential temperature 111
3.4. Equivalent-potential temperature 114
3.5. Virtual temperature 116
Chapter 4. Radiation and Light 118
4.1. The emission of radiation from bodies and the effects of the absorbed energy 118
4.2. Radiometric temperature 120
4.3. Angular distribution of radiant emission of bodies 122
4.4. Attenuation of light in the atmosphere 123
4.5. Daily and seasonal cycles of solar radiation on a surface 124
4.6. What is the colour of natural light? 130
4.7. Artificial lighting, optical filters and optical fibres 131
4.8. Deterioration to works of art caused by light 137
Chapter 5. Physics of Drop Formation and Micropore Condensation 144
5.1. How a curved water meniscus changes the equilibrium vapour tension 144
5.2. Derivation of the kelvin equation for droplets formation and micropore condensation 146
5.3. The formation of droplets in the atmosphere: homogeneous and heterogeneous nucleation 153
5.4. Bubbles 158
5.5. Micropore condensation and stone weathering 161
5.6. Adsorption isotherms 166
5.7. Freezing-thawing cycles 171
Chapter 6. Atmospheric Water and Stone Weathering 176
6.1. Acid rain, rainfall and crusts 176
6.2. Mechanisms of penetration of rain water and evaporation 187
6.3. Evaporation from a damp monument 189
6.4. Capillary suction 190
6.5. Lowering of the equilibrium vapour tension over a solution 194
6.6. Climate cycles, sea spray and salt damage 196
6.7. Some common errors that should be avoided 201
Chapter 7. Atmospheric Stability and Pollutant Dispersion 210
7.1. Introduction 210
7.2. The vertical temperature gradient and plume behaviour 213
7.3. Effects due to topographic horizontal inhomogeneity 220
7.4. The urban climate: heat island and aerodynamic disturbance 222
7.5. Dispersion and transportation of pollutants in a city 223
7.6. Wind friction near a surface 225
7.7. The vertical fluxes of heat, moisture and momentum 228
7.8. Heat balance at the soil or the monument surface 230
7.9. Main parameters used in measuring atmospheric stability and turbulence 234
7.10. Plume dispersion 242
7.11. Stability categories to evaluate the atmospheric stability 244
Chapter 8. Dry Deposition of Airborne Particulate Matter: Mechanisms and Effects 250
8.1. Introduction 250
8.2. Random walk and brownian diffusivity 252
8.3. Brownian deposition 258
8.4. Thermophoresis 260
8.5. Diffusiophoresis 263
8.6. Stefan flow 265
8.7. Gravitational settling 269
8.8. Electrophoresis 272
8.9. Photophoresis 273
8.10. Aerodynamic deposition: inertial impaction and interception 275
8.11. Adhesion of particles to paintings or other surfaces 280
8.12. Vertical distribution of particles in still air and their resuspension by turbulence 282
8.13. How soiling develops 285
8.14. What is the most appropriate heating and air conditioning system to avoid soiling? 289
8.15. Inappropriate positioning of paintings 294
8.16. Uplifting of giant particles and wind erosion 297
8.17. Kinetic energy and sand blasting 305
PART II: PERFORMING MICROCLIMATE FIELD SURVEYS 308
Chapter 9. Introduction to Field Measurements 310
9.1. Weather stations and observations for monument conservation 310
9.2. Statistical representation of the data 313
9.3. Frequency of observation 317
9.4. Length of observation period 319
9.5. Response time of a sensor 320
9.6. Essential glossary 327
Chapter 10. Measuring Temperature 330
10.1. Measuring air temperature 330
10.2. Measuring surface temperature 348
Chapter 11. Measuring Humidity 356
11.1. Measuring air humidity 356
11.2. Measuring monument humidity and air-artefact interactions 368
Chapter 12. Measuring Wind and Indoor Air Motions 378
12.1. Meteorological wind measurements 378
12.2. Measuring inside air motions 387
Chapter 13. Measuring Rainfall and Windborne Droplets 396
13.1. Meteorological precipitation measurements 397
13.2. Precipitation on monuments 400
13.3. Wet and dry deposition samplers 403
References 406
References index 422
Subject index 426