1. Outline Further Reading: Chapter 11 of the text book - boreal forest regimes - tundra regimes Natural Environments: The Atmosphere GE 101 – Spring 2007 Boston University Myneni L26: High Latitude Climates Apr-02-07 (1 of 9) - ice-sheet regimes

2. Introduction Natural Environments: The Atmosphere GE 101 – Spring 2007 Boston University Myneni L26: High Latitude Climates Apr-02-07 (2 of 9) Previously, –We looked at mid-latitude climates –Climate regimes are differentiated by their temperature characteristics as well as their precipitation characteristics –Much more varied than low-latitude climates –Six climatic regimes in the mid-latitudes Today, –We want to look at high-latitude climates –Relatively simple –Tend to be uniformly cold –Also tend to have less precipitation than in low-latitude and mid-latitude regions

3. Introduction Natural Environments: The Atmosphere GE 101 – Spring 2007 Boston University Myneni L26: High Latitude Climates Apr-02-07 (3 of 9) –Found in the sub-arctic and Arctic circle (50N-70N) –Dominated by mP, cP air masses –Also influenced by general circulation Southerly winds in southern portion of the region, with strong easterly winds over the poles –Usually associated with high seasonality in temperature and persistently dry precipitation –Results in 3 types of climate regimes –Boreal Forest Climates –Tundra Climates –Ice Sheet Climates

4. Boreal Forest Climate-1 Natural Environments: The Atmosphere GE 101 – Spring 2007 Boston University Myneni L26: High Latitude Climates Apr-02-07 (4 of 9) –Found in the interiors of continents (N. America and Eurasia) –Slight seasonality in precipitation Winter is dry Summer, it can rain from –Poleward shift of polar front –Intrusion of mid-latitude cyclones

5. Boreal Forest Climate-2 Natural Environments: The Atmosphere GE 101 – Spring 2007 Boston University Myneni L26: High Latitude Climates Apr-02-07 (5 of 9) –Most notable aspect is the strong seasonality in temperature Seasonality in declination Continental effects –Results in highest seasonality in temperatures of any of the climate regimes Typified by Boreal forests - needleleaf trees

6. Tundra Climate-1 Natural Environments: The Atmosphere GE 101 – Spring 2007 Boston University Myneni L26: High Latitude Climates Apr-02-07 (6 of 9) –Found at the coastal fringes of continents –Wide range in precipitation characteristics Moist on the Atlantic and Pacific Dry near the Arctic

7. Tundra Climate-2 Natural Environments: The Atmosphere GE 101 – Spring 2007 Boston University Myneni L26: High Latitude Climates Apr-02-07 (7 of 9) –Strong seasonality in temperature Long, cold winters Short summers However, because of the influence of the ocean, the temperatures are milder than in the Boreal forests Typified by tundra (grasses, sedges, and lichens) and permafrost

8. Ice-Sheet Climate-1 Natural Environments: The Atmosphere GE 101 – Spring 2007 Boston University Myneni L26: High Latitude Climates Apr-02-07 (8 of 9) –High latitude ice sheets over Greenland and Antarctica –Influenced by the Arctic high –Source of A and AA air mases

9. Ice-Sheet Climate-2 Natural Environments: The Atmosphere GE 101 – Spring 2007 Boston University Myneni L26: High Latitude Climates Apr-02-07 (9 of 9) –Cold all year round –Very dry No real vegetation