WEATHER MAPS TYPES OF MAPS There are 5

WEATHER MAPS

TYPES OF MAPS There are 5 basic types of maps: 1. Pressure 2. Aviation 3. Temperature 4. Streamline 5. Station Model

Pressure Maps ►Tells the air pressure ►Gives the locations of high-pressure areas and lowpressure areas

Low Pressure and Bad Weather Air warmed by the sun on the earth's surface can hold more moisture than cool air. As the warm moist air rises, it begins to cool. Eventually, the air reaches a level where it is too cool to continue to hold its moisture. At this point the moisture condenses out to become clouds. The clouds release their water as precipitation. High Pressure and Clear Weather High pressure areas are produced by cooler, heavier, sinking air. This air contains less moisture and is more stable. In the summer, high pressure usually means sustained sunshine, few clouds, low winds, high temperatures, and dry weather. In winter, the lack of cloud cover can cause the temperatures to be very cold, since the lack of clouds allows heat from the earth to travel away from the earth.

Aviation Maps Tells information necessary for safe flight of aircraft: ►Wind speed and direction ►Dew point ►Cold and warm fronts ►Icing areas ►Flight restriction information

Temperature Maps Shows temperature either in color-coded format or with the actual numbers.

Streamline Maps Shows wind patterns

Station Model Shows the weather conditions at a particular weather station (a place where weather is measured and recorded) Several conditions are measured: ►Temperature ►Humidity ►Air pressure ►Cloud cover ►Wind speed ►Wind direction Symbols are used

What information is this station model giving? Temp - 81° Winds 15 mph from the NE Dew Point – 59° Cloud Cover – 75% Air Pressure - 221

How fast is this wind blowing. . AND in what direction? 65 mph from the Northwest

Using the Symbol Key from the next slide…fill in this chart at your seat.

What is Humidity? Humidity refers to the amount of moisture (water vapor) in the surrounding air.

Relative Humidity RATIO of the amount of moisture in the air compared with the amount of moisture the air can hold at that temperature and pressure. Expressed as a percentage.

I would rather be in the desert than in North Carolina during July!!! If the air is at 90% relative humidity, sweat will not evaporate into the air. As a result, we feel much hotter than the actual temperature. If the relative humidity is low, we can feel much cooler than the actual temperature. because our sweat evaporates easily, cooling the body.

We are very sensitive to humidity. Sweating keeps our body cool and maintain its current temperature.

AGHHH my hair is HUGE, WHY? The length of a strand of human hair changes with different relative humidities. As the relative humidity increases, hair becomes longer, and as the humidity drops it becomes shorter. On very humid days, your hair actually becomes longer and this extra length causes the frizziness that gives us bad hair days.

How is Relative Humidity Measured? Sling Psychrometer It consists of two identical mercury thermometers: Evaporating water from the wick absorbs heat from thermometer bulb, causing thermometer reading to drop.

Find the difference between the DRY bulb and the WET bulb on the two thermometers Use the Relative Humidity Table Where the DRY bulb temperature and the DIFFERENCE between the two thermometers intersects…is your relative humidity. Example – If the DRY bulb temperature reading is 22°C and the DIFFERENCE between the two thermometers is 6°…the relative humidity is 53%

Practice Problems 1. Dry bulb = 12° Wet bulb = 7° 48% 2. Dry bulb = 22° Wet bulb = 20° 83% 3. Dry bulb = -10° Wet bulb = -7° 0%

Why Care about Relative Humidity? If we can’t sweat…we could overheat and DIE!!

Dew Point The temperature that air would need to cool to condense the water vapor into liquid water.

Dew Point is determined the SAME EXACT WAY that Relative Humidity is calculated…a Sling Psychrometer. You just use a DIFFERENT chart… the DEWPOINT chart. . DUH!! 1. Dry bulb = 12° Wet bulb = 7° 1° 2. Dry bulb = 22° Wet bulb = 19° 17°