Introduction Flashcards
Define Meteorology
Meteorology is the study of phenomena of the atmosphere - it includes dynamics, physics and chemistry of the atmosphere
Define Weather
The state of the atmosphere; mainly with respect to its effects upon human activities. Short term variability of the atmosphere (time scales of minutes to months)
Define Climate
Long term statistical description of the atmospheric conditions, averaged over a specific period of time - usually decades.
How far ahead can we predict?
- 3-5 days is the limit of reasonable quantitative forecasts.
- medium range forecasts (5-10) days are made, but limited to large-scale pressure field and winds, NOT detailed conditions.
- longer range forecasts (10 days - seasonal) become probabilistic forecast.
What is the persistence method of forecasting?
Assuming that tomorrow will be very much the same as the previous day.
How well does persistence forecasting work?
Works well when conditions change slowly. Quite effective for general forecasts.
What is the simple statistics: climatology method?
Given a long record of past weather on every day of the year, forecast most frequently observed weather for day of interest.
How well does the simple statistics: climatology method work?
It works quite well provided the general conditions are similar to the ‘usual’ or most common conditions for that type of year.
What is the disadvantage of the simple statistics: climatology method?
It requires long records from many years to provide reasonable statistics.
What is the analogue method of weather predicting?
Given a long record of the sequence of weather conditions, look for a past sequence that resembles the last few days to weeks, and forecast whatever followed it.
What are the problems with the analogue method?
Difficult to use effectively because of difficulty in finding a close match between current and past conditions. Again, requires records going back many years.
What is the NowCasting method of weather forecasting?
By estimating the speed at which features eg fronts and pressures are moving it allows estimation of the time of arrival. This requires measurements over a wide area and needs to be applied over a period of a few hours.
What is Physical Understanding?
An extensive set of measurements over a wide area, coupled with an understanding of physical processes allows general conditions to be assessed and forecasts to be made for a wide area a day or two ahead.
What is the thermal physical process?
Atmospheric dynamics are ultimately driven by temperature gradients arising from uneven solar heating.
What is pressure gradient forces as a physical process?
Immediate cause of horizontal motions.
