Draft Prepared by Isiorho May 29, G107 Physical Geography Draft draft draft draft drafffffffffffftttt Section II Power Point Slides

Draft Prepared by Isiorho May 29, Winds and Global Circulation Wind is air in motion Results from difference in pressure between two areas Pressure is force acting on an area Standard Pressure… Standard barometric pressure (SBP) is pressure at mean sea level Pressure Scales (numbers at mean sea level) Inches of mercury (29.92 in) Centimeters (76 cm) Millibars mb)

Draft Prepared by Isiorho May 29, Winds Pressure Gradient Force… mass movement of air High temp results in low pressure & low temp results in high pressure Pressure gradient, Friction, Gravity and Coriolis effect affect wind speed and direction Coriolis effect is due to earth’s rotation & it is the deflection of wind to the right in the northern hemisphere or to the left in the southern hemisphere (imagine yourself going in the same direction as the wind)

Draft Prepared by Isiorho May 29, Circular Moving Air Cyclone is the circular moving air mass around a low pressure center Anticyclone is a circular moving air around a high pressure center Note the pattern of cyclone/anticyclone in both the northern and southern hemispheres

Draft Prepared by Isiorho May 29, Circular Moving Air Note the pattern of cyclone/anticyclone in both the northern and southern hemispheres

Draft Prepared by Isiorho May 29, Circular Moving Air Note the convergent and divergent winds

Draft Prepared by Isiorho May 29, Circular moving air in Ft. Wayne Photos my Burnet

Draft Prepared by Isiorho May 29, Tornado Pictures from Ft. Wayne

Draft Prepared by Isiorho May 29, Global Air Pattern Low and High pressure areas of the world (linked to solar radiation/temperature) Pressure zones include low equatorial zone and midlatitude high pressure zone The NE Trades and SE Trades – air moves toward the equator from the north and south respectively Where the two trade winds collide, the area is called Intertropical Convergence Zone (ITCZ) and when they do not collide violently, the are is called Doldrum

Draft Prepared by Isiorho May 29, Global Air Pattern Contd. Global wind pattern

Draft Prepared by Isiorho May 29, Local Winds Land & Sea breezes Heating of the land and sea Mountain and Valley Winds Drainage winds (e.g. Chinook, Bora, Taku, Foehn, Mistral, & Santa Ana) Winds Aloft- winds at high altitude Geostrophic winds (Jet stream & Rosby waves)- winds flow parallel to isobars

Draft Prepared by Isiorho May 29, Ocean Currents Currents- form when wind moves over water surface in a given direction... frictional force Ocean current could be warm or cold Some ocean currents are Alaska, Agulhas, Antartic circumpacific current, Benguela, Brazi, California, Canaries, Falkland, Guinea, Gulf Stream, Kuroshio (Japan), Labrador, North Atlantic drift, N. Equatorial, Oyashio (China), Pacific, Peru, S. Equatorial, and West Wind Drift. Circular moving ocean currents are called GYRES

Draft Prepared by Isiorho May 29, Atmospheric Moisture and precipitation Humidity – amount of water vapor in the air Humidity can be measured three different ways Absolute Humidity…mass of water vapor in a given volume of air Specific humidity… the mass of water vapor in a given mass of air Relative humidity… ratio of water vapor present in the air compared to the amount of water vapor that will be present when the air is saturated at the given temperature Concept of saturation point

Draft Prepared by Isiorho May 29, When air becomes Saturated Air can become saturated either with addition of water or cooling of the air. When air cools such that it becomes saturated, the temperature at which it becomes saturated is called the DEW POINT. Cloud is the first physical evidence that the air is saturated

Draft Prepared by Isiorho May 29, Clouds Several cloud types… but they all begin as cirrus (high altitude clouds that are feather like), stratus (form layers), or cumulus (cotton bulb-like or cauliflower like) Clouds are classified based on elevations High > 7.6 km e.g. Cirrus, cirrostratus, cirro cumulus Intermediate (middle) km (stratus, stratocumulus Low 0.2 km.Cumulus, cumulonimbus Nimbus or Nimbo are prefix or suffix in cloud terminology that indicate precipitation

Draft Prepared by Isiorho May 29, Clouds

Draft Prepared by Isiorho May 29, Classification of Clouds

Draft Prepared by Isiorho May 29, Precipitation forms Drizzle Rain Snow Hail Sleet

Draft Prepared by Isiorho May 29, Classification of Precipitation Orographic- rain shadow effect Best found near the west coast… effective side is east of the west coast mountains Convectional Precipitation Cyclonic/Frontal Systems Convergent

Draft Prepared by Isiorho May 29, Weather systems Air mass- covers large area with similar temperature, pressure and moisture Air Mass properties depend on a) source region and b) region over which the wind passes The area over which an air mass forms is called the Source Region

Draft Prepared by Isiorho May 29, Types of Air Masses Classified is based on latitudinal position and underlying surface (water or land) Artic (A) mA (maritime) & cA (continental) Antarctic (AA) mAA & cAA Polar (P) mP & cP Tropical (T)mT & cP Equatorial (E) mE & cE

Draft Prepared by Isiorho May 29, Fronts When air masses move, the leading edge is called a FRONT There are four types of fronts Warm Cold Stationary Occluded

Draft Prepared by Isiorho May 29, Traveling Cyclones Wave cyclone (midlatitude and Artic regions) Tropical (Hurricanes & Typhoons) Tornado (small storm related to sever convectional activity) Why do most storms occur in Spring and Summer?

Draft Prepared by Isiorho May 29, Weather and Climate Weather involves the every day weather related activities Elements of weather include temperature, cloud types, cloud cover, wind, wind direction, fog, precipitation, sunshine, etc. Climate is the average weather condition of a given location Takes into account the extreme weather conditions also.

Draft Prepared by Isiorho May 29, Physical components of climate Radiation Sensible heat Barometric pressure Winds Relative and Specific Humidity Dew Point Cloud cover and type Fog Precipitation type and intensity Evaporation and Transpiration Cyclones

Draft Prepared by Isiorho May 29, Climate Controls Latitude Distribution of land & water Ocean current Mountain

Draft Prepared by Isiorho May 29, Climate classification Criteria Thermal regimes Precipitation Air masses and Frontal zones Koppen-Geiger climate system Five major climate groups A B C D E

Draft Prepared by Isiorho May 29, Key words Air mass, relative, specific, absolute humidity, dew point, rain shadow, pressure, cloud types, climatic controls, winds, cyclones, anticyclone, coriolis effect, winds aloft, Geostrophic wind, front types, precipitation types, climates, climographs, nimbos, nimbus, cumulonimbus, convergent, divergent