TIDAL INFORMATION
The dominant tide in the Mumbai
Harbour is the semi-diurnal tide with a period of 12 hours and 40
minutes. The following are the particulars of tidal levels related to
Chart Datum.
| Tide |
Above(+)
or Below(-)
Chart Datum |
| Highest
High Water recorded |
+
5.39 m |
| Mean
High Water Spring Tides. |
+
4.42 m |
| Mean
High Water Neap Tides. |
+
3.30 m |
| Mean
Sea Level. |
+
2.51 m |
| Mean
Low Water Neap Tides. |
+
1.86 m |
| Mean
Low Water Spring Tides. |
+
0.76 m |
| Lowest
Low Water recorded. |
-
0.46 m |
| Highest
Low Water |
+
2.74 m |
- Statistical studies
made indicate that :-
- 1. All high tides
exceed + 2.70 m.
2. About 5% of all high tides would be less than + 3.20 m.
-
WIND
General direction of wind
is from the North to the West quarter, with seasonal variations as shown
below :-
SEASONAL WIND
VARIATIONS
| Months |
Directions |
Speeds |
| 1.
Feb-May |
Mainly
from N.W. |
(Max.
8 to 10 Beaufort
Substantial 4-6 Beaufort) |
| 2.
June-Sep |
Mainly
from W.N.W. |
(Max.
8 to 10 Beaufort
Substantial 6-8 Beaufort) |
| 3.
Oct-Jan |
Mainly
from N.N.W. |
(Max.
6 to 8 Beaufort
Substantial 2-6 Beaufort) |
CYCLONES
These may occur in the
period of May/June or October/November. The last severe cyclone off the
coast of Mumbai was experienced in June 1996. Prior to this the earlier
cyclone occured in 1992.
CURRENTS
The currents in the
harbour are essentially caused by the tides and are not influenced to any
extent by monsoons etc. The tidal flow is unsteady and the magnitude and
direction of the current varies with respect to location, time and depth.
WAVES
The predominant waves are
the swell waves generated by deep sea storms. These mainly arise just
before and during the South West monsoon. The statistical analysis
indicates that most wave periods fall between 6 seconds and 10 seconds.
During the continuance of the North-East monsoon, North-Easterly winds
known as "Elephantas" blow for short durations during the months
of October-November. As the fetch and duration of these winds are limited,
the"Significant height" of the resulting waves is not likely to
exceed 1 metre with period ranging from 3 to 5 seconds.
RELATIVE HUMIDITY
& TEMPERATURE
Relative humidity ranges
from 61% to 87% being the highest in the monsoon period. During the winter
months (Nov-Jan) relative humidity ranges from 61% to 72%. Mean daily
temperature ranges from 24 Degrees C to 33 Degrees C except during the
winter period when the minimum temperature may fall to about 19 Degrees.
The hotter months are March, April, May and June.
VISIBILITY
In general, on the West
Coast, above latitude 16o N mist sometimes
develops during sunrise but disperses thereafter.
At Mumbai from November to March smog hangs over the land, obscuring
everything in view. This happens only for short periods most often shortly
after sunrise but also occasionally in the evenings. Visibility is
generally good for most part of the year.
RAINFALL
The climate of the region
has a regular seasonal variation determined by the occurrence of two annual
monsoons. The South-West monsoon period extends from June to September.
Most of the annual rainfall occurs during the South-West monsoon, the
average monthly rainfall being about 45 cm.Rain during the North-East
monsoon is slight. The average annual rainfall over 20 years is 193 cm.
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