| NATS 101 Lecture 22 Air Masses |
| What is an Air Mass? |
| Air Mass | |
| Large area (>1600 km by 1600 km) of air that contains relatively uniform, horizontal distributions of temperature and moisture. |
| How Air Masses Form |
| If surface air resides in a region for a few days, it acquires the thermal and moisture characteristics of the underlying surface. | |
| Source regions for Air Masses are: | |
| Big in area [ >>(1600 km)2 ] | |
| Dominated by persistent high pressure and light winds |
| Air Mass Source Regions |
| Contrasting source regions are | |
| Continents versus Oceans | |
| Tropics versus Poles | |
| An Air Mass is designated in terms of its Source Region |
| Air Mass Characteristics |
| Air Mass Source Regions for NA |
| Creation of cP Air Mass |
| Creation of cP Air Mass |
| Creation of mP Air Mass |
| Lake Effect Snows |
| Creation of mT and cT Air Masses |
| Contrasting Air Masses |
| Paths of cP Air Masses |
| cP Air Mass |
| Modification of cP Air Mass |
| mP Air Masses |
| cT Air Mass |
| Winter mT Pacific Air Masses |
| Weather Map with Air Masses |
| Summary |
| Air Masses | |
| Large (>1000 miles) regions with ÒuniformÓ temperature and moisture characteristics | |
| Classified by Source Region | |
| Continental (c) or Maritime (m) | |
| Polar (P) or Tropical (T) | |
| Source Regions | |
| Big in area (>>1600 km by 1600 km) | |
| Dominated by light winds (long resident times) |
| Assignment for Next Lecture |
| Topic - Fronts | |
| Reading - Ahrens pg 212-219 | |
| Problems - 8.12, 8.13 |