1. Let’s get something straight around here.

2. Weather Weather is the sum of all physical properties such as: temperature, atmospheric pressure, humidity, precipitation, sunshine, cloud cover, and wind direction and speed. These factors can change from moment to moment and are more easily identifiable by the general public.

3. Climate Climate is the average long-term weather of an area. This includes the general pattern of atmospheric or weather conditions, seasonal variations, and weather extremes averaged over a long period (at least 30 years). The two main contributing factors include temperature and precipitation.

4. Climatic Regions Tropical – between 23.5 o North and 23.5 o South. Temperate – from Tropical region to approximately 55 o North and 55 0 South. Polar – from Temperate region to 90 o North and 90 o South. Climate changes from Equator to Pole is mimicked as one moves from sea level up in elevation.

5. Climatic Regions

6. Air Circulation

7. Pressure Systems High Pressure generally indicates stable, clear weather. Low Pressure generally indicates unstable, stormy weather. Winds flow from areas of high to low pressure. The greater the pressure difference, the stronger the winds. Cold air is more dense and will “dive under” warm air. Moist warm air forced upward will form thunderheads.

8. Baltimore Climate Baltimore, located at 39.2833 o N in the mid-Atlantic coastal region of North America enjoys a maritime temperate climate. Winters are cool, but not frigid. Precipitation the Winter falls at a steady pace. Summers are very warm. Precipitation in the Summer is less frequent than Winter. Spring and Fall are mild. Precipitation falls mostly in the Spring. The proximity of the Atlantic Ocean offers a stabilizing effect on average annual temperatures. Why/How? In a word: Specific Heat

9. Baltimore Weather Who can predict? Certainly not the meteorologists. Weather is influenced by many factors (the Great Lakes, the western Maryland mountains, the Chesapeake Bay) but, the Atlantic Ocean drives the weather. What type of weather would you expect to enjoy on March 17 th in Baltimore? Record High – 85 o F Record Low – 15 o F Average High – 54 o F Average Low – 34 o F Yesterday’s High - 45 o F Yesterdays Low - 38 o F

10. Baltimore Weather We are expected to receive a “wintry mix” this afternoon/evening. Why is it unlikely that we will be have a delayed opening or “snow day” tomorrow? Warm periods in recent days have kept the temperature of the ground above freezing. The increasing angle of the Sun means that more solar radiation is reaching the Northern Hemisphere.