Weather Map Analysis Lab 7

Can include: Frontal lines Barometric pressure Isolines Temperature Frontal zones Frontal air

This is a surface weather chart. A weather map describing the state of the atmosphere over a large area at a given moment. Synoptic Map:Synoptic Map: map that shows weather conditions for a specific time.

Data are always plotted in the same position around the station symbol for consistent reading. Weather Map Analysis: Simplified Surface Station Model

Barometric Pressure NORMAL AIR PRESSURE: 950 – 1050 mb 1.insert decimal point – over 1 number from the right to the left 2.replace the missing beginning number with a 9 or 10 : a.The barometric pressure has to fall within the normal range (for our purposes) – EXAMPLE: 130 = mb

Wind Direction Measured by where wind is coming FROM Will also determine the temperatures and moisture content of the air mass Pressure Gradient Force

Isolines Isolines (lines of constant value) generally used to show spatial patterns of specific variables: 1.Isotherms: temperature 2.Isodrosotherms: dew point Typically drawn at 5° intervals 3.Isobars : barometric pressure Typically drawn at 4-mb intervals

Streamlines: used to show wind flow patterns Drawn parallel to wind barbs Begin at an upwind location End with an arrow where wind shifts abruptly Tips: 1.Look for “corridors” 2.Draw streamlines from the ‘tail’ to/towards the ‘head.’

Air Masses large body of air with relatively uniform temperature & moisture characteristics Form over large land or water surfaces Take on the temperature & moisture characteristics of the surfaces over which they formed. Classification depends on: 1.Latitude – determines temperature characteristic (upper-case letter_ 2.Nature of the surface – determines the moisture characteristic (lower- case letter) They are identified by two-letter codes Ex: cP

mE maritime equatorial cT continental tropical mT maritime tropical cP continental polar mP maritime polar cA continental arctic Types of Air Masses Is there a type of air mass missing from this list?

Fronts boundary between two unlike air masses Identified by: 1.Sharp temperature gradient 2.Sharp moisture gradient 3.Sharp change in wind direction (in a clockwise direction)

Types of Fronts 3. Stationary – neither air mass advances; air flow parallel to the boundary 1. Cold – cold air advances on warm air Known to move more quickly Vertical cloud formation 2. Warm – warm air advances on cold air Clouds form ahead of the front 4.Occluded – cold front overtakes warm front

North- Northwesterly L South- Southeasterly Easterly Winds from the North = COLD Winds from the South == WARM Winds from the East = COOL Cold front: triangles extend into the warm air Warm front: semicircles extend into the cold air.

High pressure systems are characteristic of clear skies Low Pressure systems are characteristic of precipitation and clouds

Pressure changes with temperature Air flows from areas of higher pressure to areas of lower pressure source for most winds is solar radiation (unequal heating of Earth’s surface) High Pressure = high barometric pressure. Air is dense Low Pressure = low barometric pressure. Air is light. Cold (dense) = HIGH PRESSURE Warm (less dense) = LOW PRESSURE

Coriollis Effect